> On Oct. 24, 2012, 1:23 p.m., Ivan Kelly wrote: > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreScannableTable.java, > > line 25 > > <https://reviews.apache.org/r/7314/diff/1/?file=160306#file160306line25> > > > > My question is why is it a separate interface though? Do you ever see a > > case where MetastoreTable will be implemented and not > > MetastoreScannableTable? I think the two should be merged now, and if the > > need for scan is removed in the future we can remove it from all the > > interface. This isn't going to be a public interface. > > Sijie Guo wrote: > Added my comment: In some table system, there are two kinds for table, > HASH and ORDER. For topic ownership and topic persistence info, a HASH table > is enough. While GC and ReadSubscriptions, an ORDER table is required now. > The different between MetastoreTable and MetastoreScannableTable is > MetastoreScannableTable provides order scan. > > Jiannan Wang wrote: > As sijie's comment, some key-value storages make better optimization if > online scan operation is not required. And scan is only used by GC and > ReadSubscriptions, so we separate it. > > Ivan Kelly wrote: > If a metastore doesnt provide scan then it can't do GC & read > subscriptions. This makes that metastore unusable. This is my point. > Metastore is being done to provide a single metadata interface for hw + bk. > Scan is a necessary requirement for bk + hw, therefore a table interface that > doesn't use scan is of little use.
in general, we have only two tables requires order table scan, one is ledger metadata table, the other one is subscription metadata table. but the table of persistence info and topic owner, which doesn't need a scan table. And a HASH table is more suitable for the accesses to persistence and topic owner tables. The interface of MetastoreTable also have scan interface, but it doesn't require the scan to be in order, while the interface of MetastoreScannableTable is based on MetastoreTable just adding order scan requirements to indicating it was an order table. We don't want to force all tables to be order table, since order table has its pros and cons. - Sijie ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/7314/#review12712 ----------------------------------------------------------- On Nov. 1, 2012, 4:27 p.m., Jiannan Wang wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/7314/ > ----------------------------------------------------------- > > (Updated Nov. 1, 2012, 4:27 p.m.) > > > Review request for bookkeeper. > > > Description > ------- > > We need a MetaStore interface which easy for us to plugin different scalable > k/v storage, such as HBase. > > > This addresses bug BOOKKEEPER-204. > https://issues.apache.org/jira/browse/BOOKKEEPER-204 > > > Diffs > ----- > > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MSException.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetaStore.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreCallback.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreCursor.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreException.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreFactory.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreScannableTable.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreTable.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/MetastoreTableItem.java > PRE-CREATION > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/Value.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/mock/MockMetaStore.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/mock/MockMetastoreCursor.java > PRE-CREATION > > bookkeeper-server/src/main/java/org/apache/bookkeeper/metastore/mock/MockMetastoreTable.java > PRE-CREATION > > bookkeeper-server/src/test/java/org/apache/bookkeeper/metastore/MetastoreScannableTableAsyncToSyncConverter.java > PRE-CREATION > > bookkeeper-server/src/test/java/org/apache/bookkeeper/metastore/MetastoreTableAsyncToSyncConverter.java > PRE-CREATION > > bookkeeper-server/src/test/java/org/apache/bookkeeper/metastore/TestMetaStore.java > PRE-CREATION > > Diff: https://reviews.apache.org/r/7314/diff/ > > > Testing > ------- > > > Thanks, > > Jiannan Wang > >
