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Invent an assign-hook mechanism for psql variables similar to the one

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existing for backend GUC variables, and use this to eliminate repeated
fetching/parsing of psql variables in psql's inner loops.  In a trivial
test with lots of 'select 1;' commands, psql's CPU time went down almost
10%, although of course the effect on total elapsed time was much less.
Per discussion about how to ensure the upcoming FETCH_COUNT patch doesn't
cost any performance when not being used.
This commit is contained in:
Tom Lane
2006-08-29 15:19:51 +00:00
parent b681bfdd59
commit 0434c46db0
12 changed files with 408 additions and 267 deletions
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55
src/bin/psql/variables.h
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@@ -3,62 +3,57 @@
*
* Copyright (c) 2000-2006, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/bin/psql/variables.h,v 1.18 2006/03/05 15:58:52 momjian Exp $
* $PostgreSQL: pgsql/src/bin/psql/variables.h,v 1.19 2006/08/29 15:19:51 tgl Exp $
*/
/*
* This implements a sort of variable repository. One could also think of it
* as cheap version of an associative array. In each one of these
* datastructures you can store name/value pairs.
*/
#ifndef VARIABLES_H
#define VARIABLES_H
#define VALID_VARIABLE_CHARS "abcdefghijklmnopqrstuvwxyz"\
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" "0123456789_"
/*
* This implements a sort of variable repository. One could also think of it
* as a cheap version of an associative array. In each one of these
* datastructures you can store name/value pairs. There can also be an
* "assign hook" function that is called whenever the variable's value is
* changed.
*
* An "unset" operation causes the hook to be called with newval == NULL.
*
* Note: if value == NULL then the variable is logically unset, but we are
* keeping the struct around so as not to forget about its hook function.
*/
typedef void (*VariableAssignHook) (const char *newval);
struct _variable
{
char *name;
char *value;
VariableAssignHook assign_hook;
struct _variable *next;
};
typedef struct _variable *VariableSpace;
/* Allowed chars in a variable's name */
#define VALID_VARIABLE_CHARS "abcdefghijklmnopqrstuvwxyz"\
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" "0123456789_"
VariableSpace CreateVariableSpace(void);
const char *GetVariable(VariableSpace space, const char *name);
bool GetVariableBool(VariableSpace space, const char *name);
bool VariableEquals(VariableSpace space, const char name[], const char *opt);
/* Read numeric variable, or defaultval if it is not set, or faultval if its
* value is not a valid numeric string. If allowtrail is false, this will
* include the case where there are trailing characters after the number.
*/
bool ParseVariableBool(const char *val);
int ParseVariableNum(const char *val,
int defaultval,
int faultval,
bool allowtrail);
int GetVariableNum(VariableSpace space,
const char name[],
const char *name,
int defaultval,
int faultval,
bool allowtrail);
/* Find value of variable <name> among NULL-terminated list of alternative
* options. Returns VAR_NOTSET if the variable was not set, VAR_NOTFOUND
* if its value did not occur in the list of options, or the number of the
* matching option. The first option is 1, the second is 2 and so on.
*/
enum
{
VAR_NOTSET = 0, VAR_NOTFOUND = -1};
int
SwitchVariable(VariableSpace space, const char name[],
const char *opt,...);
void PrintVariables(VariableSpace space);
bool SetVariable(VariableSpace space, const char *name, const char *value);
bool SetVariableAssignHook(VariableSpace space, const char *name, VariableAssignHook hook);
bool SetVariableBool(VariableSpace space, const char *name);
bool DeleteVariable(VariableSpace space, const char *name);