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Represent command completion tags as structs

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The backend was using strings to represent command tags and doing string
comparisons in multiple places, but that's slow and unhelpful.  Create a
new command list with a supporting structure to use instead; this is
stored in a tag-list-file that can be tailored to specific purposes with
a caller-definable C macro, similar to what we do for WAL resource
managers.  The first first such uses are a new CommandTag enum and a
CommandTagBehavior struct.

Replace numerous occurrences of char *completionTag with a
QueryCompletion struct so that the code no longer stores information
about completed queries in a cstring.  Only at the last moment, in
EndCommand(), does this get converted to a string.

EventTriggerCacheItem no longer holds an array of palloc’d tag strings
in sorted order, but rather just a Bitmapset over the CommandTags.

Author: Mark Dilger, with unsolicited help from Álvaro Herrera
Reviewed-by: John Naylor, Tom Lane
Discussion: https://postgr.es/m/981A9DB4-3F0C-4DA5-88AD-CB9CFF4D6CAD@enterprisedb.com
This commit is contained in:
Alvaro Herrera
2020-03-02 18:19:51 -03:00
parent 7b425a5283
commit 2f9661311b
39 changed files with 877 additions and 621 deletions
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30
src/backend/utils/cache/evtcache.c vendored
View File

@ -20,6 +20,7 @@
#include "catalog/pg_event_trigger.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "tcop/cmdtag.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
@ -51,7 +52,7 @@ static EventTriggerCacheStateType EventTriggerCacheState = ETCS_NEEDS_REBUILD;
static void BuildEventTriggerCache(void);
static void InvalidateEventCacheCallback(Datum arg,
int cacheid, uint32 hashvalue);
static int DecodeTextArrayToCString(Datum array, char ***cstringp);
static Bitmapset *DecodeTextArrayToBitmapset(Datum array);
/*
* Search the event cache by trigger event.
@ -180,10 +181,7 @@ BuildEventTriggerCache(void)
evttags = heap_getattr(tup, Anum_pg_event_trigger_evttags,
RelationGetDescr(rel), &evttags_isnull);
if (!evttags_isnull)
{
item->ntags = DecodeTextArrayToCString(evttags, &item->tag);
qsort(item->tag, item->ntags, sizeof(char *), pg_qsort_strcmp);
}
item->tagset = DecodeTextArrayToBitmapset(evttags);
/* Add to cache entry. */
entry = hash_search(cache, &event, HASH_ENTER, &found);
@ -215,18 +213,18 @@ BuildEventTriggerCache(void)
}
/*
* Decode text[] to an array of C strings.
* Decode text[] to a Bitmapset of CommandTags.
*
* We could avoid a bit of overhead here if we were willing to duplicate some
* of the logic from deconstruct_array, but it doesn't seem worth the code
* complexity.
*/
static int
DecodeTextArrayToCString(Datum array, char ***cstringp)
static Bitmapset *
DecodeTextArrayToBitmapset(Datum array)
{
ArrayType *arr = DatumGetArrayTypeP(array);
Datum *elems;
char **cstring;
Bitmapset *bms;
int i;
int nelems;
@ -234,13 +232,17 @@ DecodeTextArrayToCString(Datum array, char ***cstringp)
elog(ERROR, "expected 1-D text array");
deconstruct_array(arr, TEXTOID, -1, false, 'i', &elems, NULL, &nelems);
cstring = palloc(nelems * sizeof(char *));
for (i = 0; i < nelems; ++i)
cstring[i] = TextDatumGetCString(elems[i]);
for (bms = NULL, i = 0; i < nelems; ++i)
{
char *str = TextDatumGetCString(elems[i]);
bms = bms_add_member(bms, GetCommandTagEnum(str));
pfree(str);
}
pfree(elems);
*cstringp = cstring;
return nelems;
return bms;
}
/*

8
src/backend/utils/cache/plancache.c vendored
View File

@ -158,12 +158,12 @@ InitPlanCache(void)
*
* raw_parse_tree: output of raw_parser(), or NULL if empty query
* query_string: original query text
* commandTag: compile-time-constant tag for query, or NULL if empty query
* commandTag: command tag for query, or UNKNOWN if empty query
*/
CachedPlanSource *
CreateCachedPlan(RawStmt *raw_parse_tree,
const char *query_string,
const char *commandTag)
CommandTag commandTag)
{
CachedPlanSource *plansource;
MemoryContext source_context;
@ -241,12 +241,12 @@ CreateCachedPlan(RawStmt *raw_parse_tree,
*
* raw_parse_tree: output of raw_parser(), or NULL if empty query
* query_string: original query text
* commandTag: compile-time-constant tag for query, or NULL if empty query
* commandTag: command tag for query, or NULL if empty query
*/
CachedPlanSource *
CreateOneShotCachedPlan(RawStmt *raw_parse_tree,
const char *query_string,
const char *commandTag)
CommandTag commandTag)
{
CachedPlanSource *plansource;