When SQL that returns many tuples with character code conversion
is executed, the FunctionCall3/FunctionCall5 becomes a bottleneck.
Because MemSet is used to initialize FunctionCallInfoData in these
functions, a lot of cycles are spent.
<test query>
set client_encoding to 'SJIS';
select * from pg_class, pg_amop;
(This SQL is used only to get a lot of tuples, and there is no
logical meaning)
<result of profile>
Each sample counts as 0.01 seconds. % cumulative self self totaltime seconds seconds calls
s/call s/call name22.91 1.29 1.29 1562351 0.00 0.00 FunctionCall518.29 2.32 1.03
1602006 0.00 0.00 FunctionCall3 5.06 2.60 0.28 4892127 0.00 0.00 AllocSetAlloc 4.88
2.88 0.28 9781322 0.00 0.00 AllocSetFreeIndex 4.35 3.12 0.24 1587600 0.00 0.00
ExecEvalVar
Most of calls of these functions are from printtup.
FunctionCall3 is used to generate the text.
FunctionCall5 is used to character code conversion.
(printtup -> pq_sendcountedtext -> pg_server_to_client ->perform_default_encoding_conversion -> FunctionCall5)
I think that we should initialize only the fields of
FunctionCallInfoData that must be initialized.
(Such as FunctionCall1)
I have two plans to modify the code.
(a)Change FunctionCall3/FunctionCall5 like FunctionCall1. It is simple, minimum change.
(b)Define the macro that initialize FunctionCallInfoData, and use it
instead of MemSet in all FunctionCallN, DirectFunctionCallN,
OidFunctionCallN.This macro is the following.
#define InitFunctionCallInfoData(Fcinfo, Flinfo, Nargs) \ do {
\ (Fcinfo)->flinfo = Flinfo; \ (Fcinfo)->context = NULL;
\ (Fcinfo)->resultinfo = NULL; \ (Fcinfo)->isnull = false;
\ (Fcinfo)->nargs = Nargs; \ MemSet((Fcinfo)->argnull, 0, Nargs * sizeof(bool));
\ } while(0)
I think that plan(b) is better, because source code consistency
and efficiency improve.
Any comments?
regards,
---
A.Ogawa ( a_ogawa@hi-ho.ne.jp )
