[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13547981#comment-13547981 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-hadoop2 #54 (See [https://builds.apache.org/job/Hive-trunk-hadoop2/54/]) HIVE-3424. Error by upgrading a Hive 0.7.0 database to 0.8.0 (008-HIVE-2246.mysql.sql) (Alexander Alten-Lorenz via cws) (Revision 1380483) Result = ABORTED cws : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1380483 Files : * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13448018#comment-13448018 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-h0.21 #1646 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1646/]) HIVE-3424. Error by upgrading a Hive 0.7.0 database to 0.8.0 (008-HIVE-2246.mysql.sql) (Alexander Alten-Lorenz via cws) (Revision 1380483) Result = FAILURE cws : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1380483 Files : * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13161747#comment-13161747 ] Namit Jain commented on HIVE-2246: -- Note that there is a bug in the upgrade script. After running this script, the column information for all the partitions is lost. They all inherit the columns from the table definition. It is not a serious problem, as the partition column information is not really used by Hive. The only command whose results will change is: describe table T partition P; Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13161749#comment-13161749 ] Ashutosh Chauhan commented on HIVE-2246: Thanks Namit for pointing this out. HCatalog looks into the columns information of partitions, so it will have an issue. Do you have a fix or it or if you can point out which part of script has a bug, we can take a look. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13161753#comment-13161753 ] Ashutosh Chauhan commented on HIVE-2246: Also, I assume this is only while upgrading an existing metastore. Newly added partitions after upgrade or new install will not loose any information. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13149397#comment-13149397 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-h0.21 #1082 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1082/]) HIVE-2572 HIVE-2246 upgrade script changed the COLUMNS_V2.COMMENT length (Ning Zhang via namit) namit : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1201470 Files : * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13148987#comment-13148987 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-h0.21 #1079 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1079/]) HIVE-2568 HIVE-2246 upgrade script needs to drop foreign key in COLUMNS_OLD (Ning Zhang via namit) namit : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1201091 Files : * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13146787#comment-13146787 ] Hudson commented on HIVE-2246: -- Integrated in Hive-0.8.0-SNAPSHOT-h0.21 #87 (See [https://builds.apache.org/job/Hive-0.8.0-SNAPSHOT-h0.21/87/]) HIVE-2556. upgrade script 008-HIVE-2246.mysql.sql contains syntax errors. (Ning Zhang via pauly) - begin *PUBLIC* platform impact section - Bugzilla: # - end platform impact - pauly : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1199595 Files : * /hive/branches/branch-0.8/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13146794#comment-13146794 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-h0.21 #1070 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1070/]) HIVE-2556. upgrade script 008-HIVE-2246.mysql.sql contains syntax errors. (Ning Zhang via pauly) pauly : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1199593 Files : * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=1319#comment-1319 ] Hudson commented on HIVE-2246: -- Integrated in Hive-trunk-h0.21 #1059 (See [https://builds.apache.org/job/Hive-trunk-h0.21/1059/]) HIVE-2366. Metastore upgrade scripts for HIVE-2246 do not migrate indexes nor rename the old COLUMNS table (Sohan Jain via Ning Zhang) nzhang : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1197644 Files : * /hive/trunk/metastore/scripts/upgrade/derby/008-HIVE-2246.derby.sql * /hive/trunk/metastore/scripts/upgrade/derby/008-REVERT-HIVE-2246.derby.sql * /hive/trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13144490#comment-13144490 ] Hudson commented on HIVE-2246: -- Integrated in Hive-0.8.0-SNAPSHOT-h0.21 #82 (See [https://builds.apache.org/job/Hive-0.8.0-SNAPSHOT-h0.21/82/]) HIVE-2366. Metastore upgrade scripts for HIVE-2246 do not migrate indexes nor rename the old COLUMNS table (Sohan Jain via Ning Zhang) nzhang : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVNview=revrev=1197646 Files : * /hive/branches/branch-0.8/metastore/scripts/upgrade/derby/008-HIVE-2246.derby.sql * /hive/branches/branch-0.8/metastore/scripts/upgrade/derby/008-REVERT-HIVE-2246.derby.sql * /hive/branches/branch-0.8/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13083751#comment-13083751 ] Paul Yang commented on HIVE-2246: - There has been some issues identified with this patch. We will be doing some additional testing, but we might rollback so that we don't leave trunk in an unstable state. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Fix For: 0.8.0 Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13081956#comment-13081956 ] Paul Yang commented on HIVE-2246: - +1 - tests passed. Will commit. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch, HIVE-2246.8.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13081188#comment-13081188 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-08 20:55:11.546253) Review request for hive, Ning Zhang and Paul Yang. Changes --- added derby upgrade and revert-the-upgrade script Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/scripts/upgrade/derby/008-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/derby/008-REVERT-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows.
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13081202#comment-13081202 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-08 21:19:06.999293) Review request for hive, Ning Zhang and Paul Yang. Changes --- revised description for latest changes Summary (updated) --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When creating a table, create a new column descriptor every time. When altering a table, only construct a new column descriptor if the columns list has changed. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs - trunk/metastore/scripts/upgrade/derby/008-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/derby/008-REVERT-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13081209#comment-13081209 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-08 21:29:23.722825) Review request for hive, Ning Zhang and Paul Yang. Changes --- Revert the changes to describe table T partition P, so that it always shows the table T's schema. If a table's schema has changed, we do not support querying on the old partition's schema at the moment. Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When creating a table, create a new column descriptor every time. When altering a table, only construct a new column descriptor if the columns list has changed. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/scripts/upgrade/derby/008-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/derby/008-REVERT-HIVE-2246.derby.sql PRE-CREATION trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13080211#comment-13080211 ] jirapos...@reviews.apache.org commented on HIVE-2246: - bq. On 2011-07-25 06:46:04, Ning Zhang wrote: bq. trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql, line 76 bq. https://reviews.apache.org/r/1183/diff/2/?file=26824#file26824line76 bq. bq. is the CHARSET (latin1) the same as SDS? This will require the user's comments to be in latin1 which prevents UTF chars. Yes, this charset matches the same ones from the official hive schema for 0.7.0. bq. On 2011-07-25 06:46:04, Ning Zhang wrote: bq. trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql, line 206 bq. https://reviews.apache.org/r/1183/diff/2/?file=26824#file26824line206 bq. bq. can you also add migration script for derby? we support derby as a default metastore RDBMS as well. Ok, will do. I will add it in the next-next diff here. bq. On 2011-07-25 06:46:04, Ning Zhang wrote: bq. trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java, line 1752 bq. https://reviews.apache.org/r/1183/diff/2/?file=26825#file26825line1752 bq. bq. here do you check if the 'alter table' command changes the schema (columns definition)? If it just set a table property, then you don't need to create a new ColumnDescriptor right? bq. bq. Also if a table's schema got changed, a new CD will be created, but the old partition will still have the old CDs. When we query the old partition, do we use the old partitons's CD or the table's CD? bq. bq. Also in the above case, when you run 'desc table partition old_partition', do you return the old partition's CD or the table's CD? Good point; I should check whether the table columns have changed; I do this already when altering partitions. I added that in the next diff. If a table's schema changes, it does not update existing partition CDs. If we ever grab the partition object after the schema change, it will refer to its old CD, not the table's CD. However, when querying tables on the CLI, we almost always use the table's set of columns. E.g., if did: bq. create table test (a string) partitioned by (p1 string, p2 string); bq. alter table test add partition(p1=1, p2=1); bq. # populate the p1=1, p2=1 partition with some data now bq. alter table test add columns (b string) bq. select * from test where p1 = 1 and p2 = 1, it'd use the table's latest schema; i.e., return the column 'a's values and the column 'b' as all NULL. - Sohan --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/#review1176 --- On 2011-07-22 05:30:29, Sohan Jain wrote: bq. bq. --- bq. This is an automatically generated e-mail. To reply, visit: bq. https://reviews.apache.org/r/1183/ bq. --- bq. bq. (Updated 2011-07-22 05:30:29) bq. bq. bq. Review request for hive, Ning Zhang and Paul Yang. bq. bq. bq. Summary bq. --- bq. bq. This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. bq. bq. The new schema can be described as follows: bq. - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. bq. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. bq. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. bq. bq. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. bq. bq. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. bq. bq. When adding or altering a table, create a new column descriptor every time. bq. bq. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13080216#comment-13080216 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-05 20:48:05.144312) Review request for hive, Ning Zhang and Paul Yang. Changes --- -On alter table, only change the column descriptor if the columns have changed. -Fix desc table partition... to use the partition's column schema, not the table's Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13080218#comment-13080218 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-05 20:49:19.127572) Review request for hive, Ning Zhang and Paul Yang. Changes --- -Forgot to add a few files. NOTE: this is only a temporary diff; I need to add derby and postgres migration scripts. Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13080327#comment-13080327 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-08-06 01:40:49.118616) Review request for hive, Ning Zhang and Paul Yang. Changes --- -made listStorageDescriptors.. into one transaction -renamed dropStorageDescriptorCleanly to make it's functionality clearer -indents typo Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 trunk/metastore/src/model/package.jdo 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13080328#comment-13080328 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/#review1313 --- trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java https://reviews.apache.org/r/1183/#comment2984 should read 1-N actually - Sohan On 2011-08-06 01:40:49, Sohan Jain wrote: bq. bq. --- bq. This is an automatically generated e-mail. To reply, visit: bq. https://reviews.apache.org/r/1183/ bq. --- bq. bq. (Updated 2011-08-06 01:40:49) bq. bq. bq. Review request for hive, Ning Zhang and Paul Yang. bq. bq. bq. Summary bq. --- bq. bq. This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. bq. bq. The new schema can be described as follows: bq. - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. bq. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. bq. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. bq. bq. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. bq. bq. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. bq. bq. When adding or altering a table, create a new column descriptor every time. bq. bq. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. bq. bq. bq. This addresses bug HIVE-2246. bq. https://issues.apache.org/jira/browse/HIVE-2246 bq. bq. bq. Diffs bq. - bq. bq.trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION bq. trunk/metastore/src/java/org/apache/hadoop/hive/metastore/HiveMetaStore.java 1153927 bq. trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1153927 bq. trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION bq. trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1153927 bq.trunk/metastore/src/model/package.jdo 1153927 bq.trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/DDLTask.java 1153927 bq. trunk/ql/src/java/org/apache/hadoop/hive/ql/metadata/MetaDataFormatUtils.java 1153927 bq. bq. Diff: https://reviews.apache.org/r/1183/diff bq. bq. bq. Testing bq. --- bq. bq. Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. bq. bq. bq. Thanks, bq. bq. Sohan bq. bq. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch, HIVE-2246.4.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13070337#comment-13070337 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/#review1176 --- trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql https://reviews.apache.org/r/1183/#comment2467 is the CHARSET (latin1) the same as SDS? This will require the user's comments to be in latin1 which prevents UTF chars. trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql https://reviews.apache.org/r/1183/#comment2466 can you also add migration script for derby? we support derby as a default metastore RDBMS as well. trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java https://reviews.apache.org/r/1183/#comment2468 here do you check if the 'alter table' command changes the schema (columns definition)? If it just set a table property, then you don't need to create a new ColumnDescriptor right? Also if a table's schema got changed, a new CD will be created, but the old partition will still have the old CDs. When we query the old partition, do we use the old partitons's CD or the table's CD? Also in the above case, when you run 'desc table partition old_partition', do you return the old partition's CD or the table's CD? - Ning On 2011-07-22 05:30:29, Sohan Jain wrote: bq. bq. --- bq. This is an automatically generated e-mail. To reply, visit: bq. https://reviews.apache.org/r/1183/ bq. --- bq. bq. (Updated 2011-07-22 05:30:29) bq. bq. bq. Review request for hive, Ning Zhang and Paul Yang. bq. bq. bq. Summary bq. --- bq. bq. This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. bq. bq. The new schema can be described as follows: bq. - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. bq. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. bq. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. bq. bq. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. bq. bq. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. bq. bq. When adding or altering a table, create a new column descriptor every time. bq. bq. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. bq. bq. bq. This addresses bug HIVE-2246. bq. https://issues.apache.org/jira/browse/HIVE-2246 bq. bq. bq. Diffs bq. - bq. bq.trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION bq. trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1148945 bq. trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION bq. trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1148945 bq.trunk/metastore/src/model/package.jdo 1148945 bq. bq. Diff: https://reviews.apache.org/r/1183/diff bq. bq. bq. Testing bq. --- bq. bq. Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. bq. bq. bq. Thanks, bq. bq. Sohan bq. bq. Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13069389#comment-13069389 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- Review request for hive, Ning Zhang and Paul Yang. Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs - trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1148945 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1148945 trunk/metastore/src/model/package.jdo 1148945 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (HIVE-2246) Dedupe tables' column schemas from partitions in the metastore db
[ https://issues.apache.org/jira/browse/HIVE-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13069392#comment-13069392 ] jirapos...@reviews.apache.org commented on HIVE-2246: - --- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/1183/ --- (Updated 2011-07-22 05:30:29.026246) Review request for hive, Ning Zhang and Paul Yang. Changes --- Adding some files I missed in the last diff. Summary --- This patch tries to make minimal changes to the API while keeping migration short and somewhat easy to revert. The new schema can be described as follows: - CDS is a table corresponding to Column Descriptor objects. Currently, it only stores a CD_ID. - COLUMNS_V2 is a table corresponding to MFieldSchema objects, or columns. A Column Descriptor holds a list of columns. COLUMNS_V2 has a foreign key to the CD_ID to which it belongs. - SDS was modified to reference a Column Descriptor. So SDS now has a foreign key to a CD_ID which describes its columns. During migration, we create Column Descriptors for tables in a straightforward manner: their columns are now just wrapped inside a column descriptor. The SDS of partitions use their parent table's column descriptor, since currently a partition and its table share the same list of columns. When altering or adding a partition, give it it's parent table's column descriptor IF the columns they describe are the same. Otherwise, create a new column descriptor for its columns. When adding or altering a table, create a new column descriptor every time. Whenever you drop a storage descriptor (e.g, when dropping tables or partitions), check to see if the related column descriptor has any other references in the table. That is, check to see if any other storage descriptors point to that column descriptor. If none do, then delete that column descriptor. This check is in place so we don't have unreferenced column descriptors and columns hanging around after schema evolution for tables. This addresses bug HIVE-2246. https://issues.apache.org/jira/browse/HIVE-2246 Diffs (updated) - trunk/metastore/scripts/upgrade/mysql/008-HIVE-2246.mysql.sql PRE-CREATION trunk/metastore/src/java/org/apache/hadoop/hive/metastore/ObjectStore.java 1148945 trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MColumnDescriptor.java PRE-CREATION trunk/metastore/src/model/org/apache/hadoop/hive/metastore/model/MStorageDescriptor.java 1148945 trunk/metastore/src/model/package.jdo 1148945 Diff: https://reviews.apache.org/r/1183/diff Testing --- Passes facebook's regression testing and all existing test cases. In one instance, before migration, the overhead involved with storage descriptors and columns was ~11 GB. After migration, the overhead was ~1.5 GB. Thanks, Sohan Dedupe tables' column schemas from partitions in the metastore db - Key: HIVE-2246 URL: https://issues.apache.org/jira/browse/HIVE-2246 Project: Hive Issue Type: Improvement Components: Metastore Reporter: Sohan Jain Assignee: Sohan Jain Attachments: HIVE-2246.2.patch, HIVE-2246.3.patch Note: this patch proposes a schema change, and is therefore incompatible with the current metastore. We can re-organize the JDO models to reduce space usage to keep the metastore scalable for the future. Currently, partitions are the fastest growing objects in the metastore, and the metastore keeps a separate copy of the columns list for each partition. We can normalize the metastore db by decoupling Columns from Storage Descriptors and not storing duplicate lists of the columns for each partition. An idea is to create an additional level of indirection with a Column Descriptor that has a list of columns. A table has a reference to its latest Column Descriptor (note: a table may have more than one Column Descriptor in the case of schema evolution). Partitions and Indexes can reference the same Column Descriptors as their parent table. Currently, the COLUMNS table in the metastore has roughly (number of partitions + number of tables) * (average number of columns pertable) rows. We can reduce this to (number of tables) * (average number of columns per table) rows, while incurring a small cost proportional to the number of tables to store the Column Descriptors. Please see the latest review board for additional implementation details. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
