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Add COST and ROWS options to CREATE/ALTER FUNCTION, plus underlying pg_proc

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columns procost and prorows, to allow simple user adjustment of the estimated
cost of a function call, as well as control of the estimated number of rows
returned by a set-returning function.  We might eventually wish to extend this
to allow function-specific estimation routines, but there seems to be
consensus that we should try a simple constant estimate first.  In particular
this provides a relatively simple way to control the order in which different
WHERE clauses are applied in a plan node, which is a Good Thing in view of the
fact that the recent EquivalenceClass planner rewrite made that much less
predictable than before.
This commit is contained in:
Tom Lane
2007-01-22 01:35:23 +00:00
parent a85e9c61e5
commit 5a7471c307
27 changed files with 2550 additions and 2090 deletions
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110
src/backend/commands/functioncmds.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.81 2007/01/05 22:19:26 momjian Exp $
* $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.82 2007/01/22 01:35:20 tgl Exp $
*
* DESCRIPTION
* These routines take the parse tree and pick out the
@ -273,7 +273,9 @@ static bool
compute_common_attribute(DefElem *defel,
DefElem **volatility_item,
DefElem **strict_item,
DefElem **security_item)
DefElem **security_item,
DefElem **cost_item,
DefElem **rows_item)
{
if (strcmp(defel->defname, "volatility") == 0)
{
@ -296,6 +298,20 @@ compute_common_attribute(DefElem *defel,
*security_item = defel;
}
else if (strcmp(defel->defname, "cost") == 0)
{
if (*cost_item)
goto duplicate_error;
*cost_item = defel;
}
else if (strcmp(defel->defname, "rows") == 0)
{
if (*rows_item)
goto duplicate_error;
*rows_item = defel;
}
else
return false;
@ -337,7 +353,9 @@ compute_attributes_sql_style(List *options,
char **language,
char *volatility_p,
bool *strict_p,
bool *security_definer)
bool *security_definer,
float4 *procost,
float4 *prorows)
{
ListCell *option;
DefElem *as_item = NULL;
@ -345,6 +363,8 @@ compute_attributes_sql_style(List *options,
DefElem *volatility_item = NULL;
DefElem *strict_item = NULL;
DefElem *security_item = NULL;
DefElem *cost_item = NULL;
DefElem *rows_item = NULL;
foreach(option, options)
{
@ -369,7 +389,9 @@ compute_attributes_sql_style(List *options,
else if (compute_common_attribute(defel,
&volatility_item,
&strict_item,
&security_item))
&security_item,
&cost_item,
&rows_item))
{
/* recognized common option */
continue;
@ -407,6 +429,22 @@ compute_attributes_sql_style(List *options,
*strict_p = intVal(strict_item->arg);
if (security_item)
*security_definer = intVal(security_item->arg);
if (cost_item)
{
*procost = defGetNumeric(cost_item);
if (*procost <= 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("COST must be positive")));
}
if (rows_item)
{
*prorows = defGetNumeric(rows_item);
if (*prorows <= 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("ROWS must be positive")));
}
}
@ -519,6 +557,8 @@ CreateFunction(CreateFunctionStmt *stmt)
bool isStrict,
security;
char volatility;
float4 procost;
float4 prorows;
HeapTuple languageTuple;
Form_pg_language languageStruct;
List *as_clause;
@ -537,10 +577,14 @@ CreateFunction(CreateFunctionStmt *stmt)
isStrict = false;
security = false;
volatility = PROVOLATILE_VOLATILE;
procost = -1; /* indicates not set */
prorows = -1; /* indicates not set */
/* override attributes from explicit list */
compute_attributes_sql_style(stmt->options,
&as_clause, &language, &volatility, &isStrict, &security);
&as_clause, &language,
&volatility, &isStrict, &security,
&procost, &prorows);
/* Convert language name to canonical case */
languageName = case_translate_language_name(language);
@ -645,6 +689,32 @@ CreateFunction(CreateFunctionStmt *stmt)
prosrc_str = funcname;
}
/*
* Set default values for COST and ROWS depending on other parameters;
* reject ROWS if it's not returnsSet. NB: pg_dump knows these default
* values, keep it in sync if you change them.
*/
if (procost < 0)
{
/* SQL and PL-language functions are assumed more expensive */
if (languageOid == INTERNALlanguageId ||
languageOid == ClanguageId)
procost = 1;
else
procost = 100;
}
if (prorows < 0)
{
if (returnsSet)
prorows = 1000;
else
prorows = 0; /* dummy value if not returnsSet */
}
else if (!returnsSet)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("ROWS is not applicable when function does not return a set")));
/*
* And now that we have all the parameters, and know we're permitted to do
* so, go ahead and create the function.
@ -665,7 +735,9 @@ CreateFunction(CreateFunctionStmt *stmt)
parameterTypes,
PointerGetDatum(allParameterTypes),
PointerGetDatum(parameterModes),
PointerGetDatum(parameterNames));
PointerGetDatum(parameterNames),
procost,
prorows);
}
@ -1012,6 +1084,8 @@ AlterFunction(AlterFunctionStmt *stmt)
DefElem *volatility_item = NULL;
DefElem *strict_item = NULL;
DefElem *security_def_item = NULL;
DefElem *cost_item = NULL;
DefElem *rows_item = NULL;
rel = heap_open(ProcedureRelationId, RowExclusiveLock);
@ -1046,7 +1120,9 @@ AlterFunction(AlterFunctionStmt *stmt)
if (compute_common_attribute(defel,
&volatility_item,
&strict_item,
&security_def_item) == false)
&security_def_item,
&cost_item,
&rows_item) == false)
elog(ERROR, "option \"%s\" not recognized", defel->defname);
}
@ -1056,6 +1132,26 @@ AlterFunction(AlterFunctionStmt *stmt)
procForm->proisstrict = intVal(strict_item->arg);
if (security_def_item)
procForm->prosecdef = intVal(security_def_item->arg);
if (cost_item)
{
procForm->procost = defGetNumeric(cost_item);
if (procForm->procost <= 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("COST must be positive")));
}
if (rows_item)
{
procForm->prorows = defGetNumeric(rows_item);
if (procForm->prorows <= 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("ROWS must be positive")));
if (!procForm->proretset)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("ROWS is not applicable when function does not return a set")));
}
/* Do the update */
simple_heap_update(rel, &tup->t_self, tup);