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| author | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2020-04-07 16:22:13 -0400 |
|---|---|---|
| committer | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2020-04-07 16:22:13 -0400 |
| commit | 357889eb17bb9c9336c4f324ceb1651da616fe57 (patch) | |
| tree | ef30422c7a6ebc2844492bd045ffbfeb30e54516 /src/backend/utils/adt/ruleutils.c | |
| parent | 26a944cf29ba67bb49f42656dd2be98fe2485f5f (diff) | |
| download | postgresql-357889eb17bb9c9336c4f324ceb1651da616fe57.tar.gz postgresql-357889eb17bb9c9336c4f324ceb1651da616fe57.zip | |
Support FETCH FIRST WITH TIES
WITH TIES is an option to the FETCH FIRST N ROWS clause (the SQL
standard's spelling of LIMIT), where you additionally get rows that
compare equal to the last of those N rows by the columns in the
mandatory ORDER BY clause.
There was a proposal by Andrew Gierth to implement this functionality in
a more powerful way that would yield more features, but the other patch
had not been finished at this time, so we decided to use this one for
now in the spirit of incremental development.
Author: Surafel Temesgen <surafel3000@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Discussion: https://postgr.es/m/CALAY4q9ky7rD_A4vf=FVQvCGngm3LOes-ky0J6euMrg=_Se+ag@mail.gmail.com
Discussion: https://postgr.es/m/87o8wvz253.fsf@news-spur.riddles.org.uk
Diffstat (limited to 'src/backend/utils/adt/ruleutils.c')
| -rw-r--r-- | src/backend/utils/adt/ruleutils.c | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index f6cf7e72a1e..695d8c32284 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -5243,7 +5243,10 @@ get_select_query_def(Query *query, deparse_context *context, force_colno, context); } - /* Add the LIMIT clause if given */ + /* + * Add the LIMIT/OFFSET clauses if given. If non-default options, use the + * standard spelling of LIMIT. + */ if (query->limitOffset != NULL) { appendContextKeyword(context, " OFFSET ", @@ -5252,13 +5255,23 @@ get_select_query_def(Query *query, deparse_context *context, } if (query->limitCount != NULL) { - appendContextKeyword(context, " LIMIT ", - -PRETTYINDENT_STD, PRETTYINDENT_STD, 0); - if (IsA(query->limitCount, Const) && - ((Const *) query->limitCount)->constisnull) - appendStringInfoString(buf, "ALL"); - else + if (query->limitOption == LIMIT_OPTION_WITH_TIES) + { + appendContextKeyword(context, " FETCH FIRST ", + -PRETTYINDENT_STD, PRETTYINDENT_STD, 0); get_rule_expr(query->limitCount, context, false); + appendStringInfo(buf, " ROWS WITH TIES"); + } + else + { + appendContextKeyword(context, " LIMIT ", + -PRETTYINDENT_STD, PRETTYINDENT_STD, 0); + if (IsA(query->limitCount, Const) && + ((Const *) query->limitCount)->constisnull) + appendStringInfoString(buf, "ALL"); + else + get_rule_expr(query->limitCount, context, false); + } } /* Add FOR [KEY] UPDATE/SHARE clauses if present */ |