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https://issues.apache.org/jira/browse/TRAFODION-2037?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15379813#comment-15379813
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ASF GitHub Bot commented on TRAFODION-2037:
-------------------------------------------
Github user anoopsharma00 commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/565#discussion_r71015784
--- Diff: core/sql/parser/sqlparser.y ---
@@ -16026,13 +16027,30 @@ exe_util_init_hbase : TOK_INITIALIZE TOK_TRAFODION
DDLExpr * de = new(PARSERHEAP()) DDLExpr(TRUE, FALSE, TRUE,
FALSE,
FALSE, FALSE,
- FALSE, FALSE, FALSE,
+ FALSE, FALSE, FALSE,
FALSE,
--- End diff --
In the beginning there were very limited variation to DDLExpr class so
param approach was ok.
But now that there are many more options and variations to DDLExpr, it will
be better to
set the bit flags instead of adding new params.
Maybe someone can clean this up at some point and change the callers to set
bit flags
when DDLExpr class is created in parser.
> Improve DDL concurrency
> -----------------------
>
> Key: TRAFODION-2037
> URL: https://issues.apache.org/jira/browse/TRAFODION-2037
> Project: Apache Trafodion
> Issue Type: Improvement
> Components: sql-cmu
> Affects Versions: 2.1-incubating
> Environment: All
> Reporter: David Wayne Birdsall
> Assignee: David Wayne Birdsall
>
> In CmpSeabaseDDL::getSeabaseUserTableDesc
> (core/sql/sqlcomp/CmpSeabaseDDLtable.cpp), the code executes the following
> query:
> select trim(O.catalog_name || '.' || '\"' || O.schema_name || '\"' || '.' ||
> '\"' || O.object_name || '\"' ) constr_name, trim(O2.catalog_name || '.' ||
> '\"' || O2.schema_name || '\"' || '.' || '\"' || O2.object_name || '\"' )
> table_name from %s.\"%s\".%s U, %s.\"%s\".%s O, %s.\"%s\".%s O2, %s.\"%s\".%s
> T where O.object_uid = U.foreign_constraint_uid and O2.object_uid =
> T.table_uid and T.constraint_uid = U.foreign_constraint_uid and
> U.unique_constraint_uid = %Ld order by 2, 1
> The plan for this query does a full scan of TABLE_CONSTRAINTS, and joins that
> to OBJECTS_UNIQ_IDX. So all rows of TABLE_CONSTRAINTS are read, and many if
> not most rows of OBJECTS_UNIQ_IDX.
> Analyzing the query plan, the full scan is inherent. The only known
> information we have for TABLE_CONSTRAINTS is CONSTRAINT_UID, which is the
> second column of the key. The first column has high UEC so MDAM is not a
> possibility.
> Creating this large read set conflicts with many write transactions to
> metadata, decreasing DDL concurrency.
> As an experiment, I added an index to the metadata on
> TABLE_CONSTRAINTS(CONSTRAINT_UID). I found I had to add a CQS as well to
> force it to avoid a full scan. With this change, I found that DDL concurrency
> was much improved. So, the proposal in this JIRA is to add this index and CQS.
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