[CBRD-24537] Improve the performance of MERGE query by using NOT EXISTS sub-query #3919
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beyondykk9
requested review from
ctshim,
hgryoo,
hyunikn,
shparkcubrid and
youngjinj
ctshim
reviewed
Nov 20, 2022
ctshim
approved these changes
Nov 20, 2022
shparkcubrid
approved these changes
Nov 21, 2022
hyunikn
approved these changes
Nov 21, 2022
youngjinj
reviewed
Nov 22, 2022
Comment on lines
+25213
to
+25226
| if (expr) | ||
| { | ||
| if (expr->info.expr.arg1) | ||
| { | ||
| parser_free_tree (parser, expr->info.expr.arg1); | ||
| corr_subq = NULL; | ||
| } | ||
| parser_free_tree (parser, expr); | ||
| } | ||
|
|
||
| if (corr_subq) | ||
| { | ||
| parser_free_tree (parser, corr_subq); | ||
| } |
There was a problem hiding this comment.
How about below?
Suggested change
| if (expr) | |
| { | |
| if (expr->info.expr.arg1) | |
| { | |
| parser_free_tree (parser, expr->info.expr.arg1); | |
| corr_subq = NULL; | |
| } | |
| parser_free_tree (parser, expr); | |
| } | |
| if (corr_subq) | |
| { | |
| parser_free_tree (parser, corr_subq); | |
| } | |
| if (corr_subq) | |
| { | |
| parser_free_tree (parser, corr_subq); | |
| } | |
| if (expr) | |
| { | |
| parser_free_tree (parser, expr); | |
| } |
There was a problem hiding this comment.
This code sequence is right because the expr could be assigend to corr_subq.
youngjinj
reviewed
Nov 22, 2022
| @@ -25111,7 +25111,7 @@ pt_to_merge_update_query (PARSER_CONTEXT * parser, PT_NODE * select_list, PT_MER | |||
| PT_NODE * | |||
| pt_to_merge_insert_query (PARSER_CONTEXT * parser, PT_NODE * select_list, PT_MERGE_INFO * info) | |||
| { | |||
| PT_NODE *subq, *corr_subq, *expr, *and_expr, *value; | |||
| PT_NODE *subq, *corr_subq = NULL, *expr = NULL, *and_expr = NULL, *value = NULL; | |||
There was a problem hiding this comment.
It is trivial.
Suggested change
| PT_NODE *subq, *corr_subq = NULL, *expr = NULL, *and_expr = NULL, *value = NULL; | |
| PT_NODE *subq = NULL, *corr_subq = NULL, *expr = NULL, *and_expr = NULL, *value = NULL; |
There was a problem hiding this comment.
subq is always assigned some address as new node.
youngjinj
approved these changes
Nov 22, 2022
hgryoo
approved these changes
Nov 22, 2022
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http://jira.cubrid.org/browse/CBRD-24537
The MERGE query's "NOT MATCHED" part is rewritten by using COUNT query for checking "NOT MATCHED", however, the performance of COUNT query is not good compared with NOT EXISTS query.
We will enhance the performance of the MERGE query by using "NOT EXISTS" sub-query instead of COUNT query.