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Arrange for SET LOCAL's effects to persist until the end of the current top

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transaction, unless rolled back or overridden by a SET clause for the same
variable attached to a surrounding function call.  Per discussion, these
seem the best semantics.  Note that this is an INCOMPATIBLE CHANGE: in 8.0
through 8.2, SET LOCAL's effects disappeared at subtransaction commit
(leading to behavior that made little sense at the SQL level).

I took advantage of the opportunity to rewrite and simplify the GUC variable
save/restore logic a little bit.  The old idea of a "tentative" value is gone;
it was a hangover from before we had a stack.  Also, we no longer need a stack
entry for every nesting level, but only for those in which a variable's value
actually changed.
This commit is contained in:
Tom Lane
2007-09-11 00:06:42 +00:00
parent b366562e43
commit 82a47982f3
16 changed files with 814 additions and 510 deletions
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39
src/include/utils/guc_tables.h
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@ -7,7 +7,7 @@
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/include/utils/guc_tables.h,v 1.34 2007/09/10 00:57:22 tgl Exp $
* $PostgreSQL: pgsql/src/include/utils/guc_tables.h,v 1.35 2007/09/11 00:06:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -79,18 +79,27 @@ enum config_group
};
/*
* Stack entry for saving the state of a variable prior to the current
* transaction
* Stack entry for saving the state a variable had prior to an uncommitted
* transactional change
*/
typedef enum
{
/* This is almost GucAction, but we need a fourth state for SET+LOCAL */
GUC_SAVE, /* entry caused by function SET option */
GUC_SET, /* entry caused by plain SET command */
GUC_LOCAL, /* entry caused by SET LOCAL command */
GUC_SET_LOCAL /* entry caused by SET then SET LOCAL */
} GucStackState;
typedef struct guc_stack
{
struct guc_stack *prev; /* previous stack item, if any */
int nest_level; /* nesting depth of cur transaction */
int status; /* previous status bits, see below */
GucSource tentative_source; /* source of the tentative_value */
GucSource source; /* source of the actual value */
union config_var_value tentative_val; /* previous tentative val */
union config_var_value value; /* previous actual value */
int nest_level; /* nesting depth at which we made entry */
GucStackState state; /* see enum above */
GucSource source; /* source of the prior value */
union config_var_value prior; /* previous value of variable */
union config_var_value masked; /* SET value in a GUC_SET_LOCAL entry */
/* masked value's source must be PGC_S_SESSION, so no need to store it */
} GucStack;
/*
@ -113,9 +122,8 @@ struct config_generic
enum config_type vartype; /* type of variable (set only at startup) */
int status; /* status bits, see below */
GucSource reset_source; /* source of the reset_value */
GucSource tentative_source; /* source of the tentative_value */
GucSource source; /* source of the current actual value */
GucStack *stack; /* stacked outside-of-transaction states */
GucStack *stack; /* stacked prior values */
};
/* bit values in flags field */
@ -141,10 +149,7 @@ struct config_generic
#define GUC_UNIT_TIME 0x7000 /* mask for MS, S, MIN */
/* bit values in status field */
#define GUC_HAVE_TENTATIVE 0x0001 /* tentative value is defined */
#define GUC_HAVE_LOCAL 0x0002 /* a SET LOCAL has been executed */
#define GUC_HAVE_STACK 0x0004 /* we have stacked prior value(s) */
#define GUC_IS_IN_FILE 0x0008 /* found it in config file */
#define GUC_IS_IN_FILE 0x0001 /* found it in config file */
/*
* Caution: the GUC_IS_IN_FILE bit is transient state for ProcessConfigFile.
* Do not assume that its value represents useful information elsewhere.
@ -163,7 +168,6 @@ struct config_bool
GucShowHook show_hook;
/* variable fields, initialized at runtime: */
bool reset_val;
bool tentative_val;
};
struct config_int
@ -178,7 +182,6 @@ struct config_int
GucShowHook show_hook;
/* variable fields, initialized at runtime: */
int reset_val;
int tentative_val;
};
struct config_real
@ -193,7 +196,6 @@ struct config_real
GucShowHook show_hook;
/* variable fields, initialized at runtime: */
double reset_val;
double tentative_val;
};
struct config_string
@ -206,7 +208,6 @@ struct config_string
GucShowHook show_hook;
/* variable fields, initialized at runtime: */
char *reset_val;
char *tentative_val;
};
/* constant tables corresponding to enums above and in guc.h */