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Clean up and simplify code in a couple of set-returning functions

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The following set-returning functions have their logic simplified, to be
more consistent with other in-core areas:
- pg_prepared_statement()'s tuple descriptor is now created with
get_call_result_type() instead of being created from scratch, saving
from some duplication with pg_proc.dat.
- show_all_file_settings(), similarly, now uses get_call_result_type()
to build its tuple descriptor instead of creating it from scratch.
- pg_options_to_table() made use of a static routine called only once.
This commit removes this internal routine to make the function easier to
follow.
- pg_config() was using a unique logic style, doing checks on the tuple
descriptor passed down in expectedDesc, but it has no need to do so.
This switches the function to use a tuplestore with a tuple descriptor
retrieved from get_call_result_type(), instead.

This simplifies an upcoming patch aimed at refactoring the way
tuplestores are created and checked in set-returning functions, this
change making sense as its own independent cleanup by shaving some
code.

Author: Melanie Plageman, Michael Paquier
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/CAAKRu_azyd1Z3W_r7Ou4sorTjRCs+PxeHw1CWJeXKofkE6TuZg@mail.gmail.com
This commit is contained in:
Michael Paquier
2022-02-24 16:11:34 +09:00
parent 04e706d423
commit fcc28178c6
5 changed files with 50 additions and 130 deletions
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31
src/backend/commands/prepare.c
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@@ -22,6 +22,7 @@
#include "catalog/pg_type.h"
#include "commands/createas.h"
#include "commands/prepare.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
@@ -716,30 +717,13 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not allowed in this context")));
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* need to build tuplestore in query context */
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
/*
* build tupdesc for result tuples. This must match the definition of the
* pg_prepared_statements view in system_views.sql
*/
tupdesc = CreateTemplateTupleDesc(7);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "statement",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "prepare_time",
TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "parameter_types",
REGTYPEARRAYOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "from_sql",
BOOLOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "generic_plans",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 7, "custom_plans",
INT8OID, -1, 0);
/*
* We put all the tuples into a tuplestore in one scan of the hashtable.
* This avoids any issue of the hashtable possibly changing between calls.
@@ -747,6 +731,9 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
tupstore =
tuplestore_begin_heap(rsinfo->allowedModes & SFRM_Materialize_Random,
false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
/* generate junk in short-term context */
MemoryContextSwitchTo(oldcontext);
@@ -778,10 +765,6 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
}
}
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
return (Datum) 0;
}