From 84ec3f6db7691085a364f7dae01e13776be0c6a3 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Wed, 13 Sep 2017 18:41:50 -0700 Subject: [PATCH 3/8] Improve performance of SendRowDescriptionMessage. Using the new pqformat functions yields performance for statements with a noticeable number of rows. The function itself is more than twice as fast. --- src/backend/access/common/printtup.c | 156 ++++++++++++++++++++++++++--------- 1 file changed, 118 insertions(+), 38 deletions(-) diff --git a/src/backend/access/common/printtup.c b/src/backend/access/common/printtup.c index 20d20e623e..894f89b63c 100644 --- a/src/backend/access/common/printtup.c +++ b/src/backend/access/common/printtup.c @@ -32,6 +32,8 @@ static bool printtup_internal_20(TupleTableSlot *slot, DestReceiver *self); static void printtup_shutdown(DestReceiver *self); static void printtup_destroy(DestReceiver *self); +static void SendRowDescriptionCols_2(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats); +static void SendRowDescriptionCols_3(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats); /* ---------------------------------------------------------------- * printtup / debugtup support @@ -189,12 +191,118 @@ SendRowDescriptionMessage(TupleDesc typeinfo, List *targetlist, int16 *formats) { int natts = typeinfo->natts; int proto = PG_PROTOCOL_MAJOR(FrontendProtocol); + static StringInfo rowDescriptionBuf = NULL; + + /* + * As this routine is executed for every single query, it can be a + * pq_sendstring_prebottleneck. To avoid unnecessary allocator overhead + * reuse a single buffer. That means we'll never shrink below the largest + * row-description sent, but that seems acceptable given the limited size. + */ + if (unlikely(!rowDescriptionBuf)) + { + MemoryContext oldContext = MemoryContextSwitchTo(TopMemoryContext); + rowDescriptionBuf = makeStringInfo(); + MemoryContextSwitchTo(oldContext); + } + + /* tuple descriptor message type */ + pq_beginmessage_pre(rowDescriptionBuf, 'T'); + /* # of attrs in tuples */ + pq_sendint(rowDescriptionBuf, natts, 2); + + if (proto >= 3) + SendRowDescriptionCols_3(rowDescriptionBuf, typeinfo, targetlist, + formats); + else + SendRowDescriptionCols_2(rowDescriptionBuf, typeinfo, targetlist, + formats); + + pq_endmessage_keep(rowDescriptionBuf); +} + +/* + * Send description for each column when using v3+ protocol + */ +static void +SendRowDescriptionCols_3(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats) +{ + int natts = typeinfo->natts; int i; - StringInfoData buf; ListCell *tlist_item = list_head(targetlist); - pq_beginmessage(&buf, 'T'); /* tuple descriptor message type */ - pq_sendint(&buf, natts, 2); /* # of attrs in tuples */ + /* + * Prealloc memory for the entire message to be sent. That allows to use + * the significantly faster inline pqformat.h functions and to avoid + * reallocations. Have to overestimate the size of the column-names, to + * account for character set overhead. + */ + enlargeStringInfo(buf, (NAMEDATALEN * MAX_CONVERSION_GROWTH /* attname */ + + sizeof(int32) /* attlen */ + + sizeof(int32) /* resorigtbl */ + + sizeof(int16) /* resorigcol */ + + sizeof(Oid) /* atttypid */ + + sizeof(int16) /* attlen */ + + sizeof(int32) /* attypmod */ + ) * natts); + + for (i = 0; i < natts; ++i) + { + Form_pg_attribute att = TupleDescAttr(typeinfo, i); + Oid atttypid = att->atttypid; + int32 atttypmod = att->atttypmod; + int32 resorigtbl; + int32 resorigcol; + int16 format; + + /* + * If column is a domain, send the base type and typmod + * instead. Lookup before sending any ints, for efficiency. + */ + atttypid = getBaseTypeAndTypmod(atttypid, &atttypmod); + + /* Do we have a non-resjunk tlist item? */ + while (tlist_item && + ((TargetEntry *) lfirst(tlist_item))->resjunk) + tlist_item = lnext(tlist_item); + if (tlist_item) + { + TargetEntry *tle = (TargetEntry *) lfirst(tlist_item); + + resorigtbl = tle->resorigtbl; + resorigcol = tle->resorigcol; + tlist_item = lnext(tlist_item); + } + else + { + /* No info available, so send zeroes */ + resorigtbl = 0; + resorigcol = 0; + } + + if (formats) + format = formats[i]; + else + format = 0; + + pq_sendstring_pre(buf, NameStr(att->attname)); + pq_sendint32_pre(buf, resorigtbl); + pq_sendint16_pre(buf, resorigcol); + pq_sendint32_pre(buf, atttypid); + pq_sendint16_pre(buf, att->attlen); + pq_sendint32_pre(buf, atttypmod); + pq_sendint16_pre(buf, format); + } +} + +/* + * Send description for each column when using v2 protocol + */ +static void +SendRowDescriptionCols_2(StringInfo buf, TupleDesc typeinfo, List *targetlist, int16 *formats) +{ + int natts = typeinfo->natts; + int i; for (i = 0; i < natts; ++i) { @@ -202,44 +310,16 @@ SendRowDescriptionMessage(TupleDesc typeinfo, List *targetlist, int16 *formats) Oid atttypid = att->atttypid; int32 atttypmod = att->atttypmod; - pq_sendstring(&buf, NameStr(att->attname)); - /* column ID info appears in protocol 3.0 and up */ - if (proto >= 3) - { - /* Do we have a non-resjunk tlist item? */ - while (tlist_item && - ((TargetEntry *) lfirst(tlist_item))->resjunk) - tlist_item = lnext(tlist_item); - if (tlist_item) - { - TargetEntry *tle = (TargetEntry *) lfirst(tlist_item); - - pq_sendint(&buf, tle->resorigtbl, 4); - pq_sendint(&buf, tle->resorigcol, 2); - tlist_item = lnext(tlist_item); - } - else - { - /* No info available, so send zeroes */ - pq_sendint(&buf, 0, 4); - pq_sendint(&buf, 0, 2); - } - } /* If column is a domain, send the base type and typmod instead */ atttypid = getBaseTypeAndTypmod(atttypid, &atttypmod); - pq_sendint(&buf, (int) atttypid, sizeof(atttypid)); - pq_sendint(&buf, att->attlen, sizeof(att->attlen)); - pq_sendint(&buf, atttypmod, sizeof(atttypmod)); - /* format info appears in protocol 3.0 and up */ - if (proto >= 3) - { - if (formats) - pq_sendint(&buf, formats[i], 2); - else - pq_sendint(&buf, 0, 2); - } + + pq_sendstring(buf, NameStr(att->attname)); + /* column ID only info appears in protocol 3.0 and up */ + pq_sendint(buf, (int) atttypid, sizeof(atttypid)); + pq_sendint(buf, att->attlen, sizeof(att->attlen)); + pq_sendint(buf, atttypmod, sizeof(atttypmod)); + /* format info only appears in protocol 3.0 and up */ } - pq_endmessage(&buf); } /* -- 2.14.1.536.g6867272d5b.dirty