greenplumn variable 源码
greenplumn variable 代码
文件路径：/src/backend/commands/variable.c
/*-------------------------------------------------------------------------
*
* variable.c
* Routines for handling specialized SET variables.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/commands/variable.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include "access/htup_details.h"
#include "access/parallel.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "catalog/pg_authid.h"
#include "cdb/cdbvars.h"
#include "commands/variable.h"
#include "miscadmin.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/syscache.h"
#include "utils/snapmgr.h"
#include "utils/timestamp.h"
#include "utils/varlena.h"
#include "mb/pg_wchar.h"
/*
* DATESTYLE
*/
/*
* check_datestyle: GUC check_hook for datestyle
*/
bool
check_datestyle(char **newval, void **extra, GucSource source)
{
int newDateStyle = DateStyle;
int newDateOrder = DateOrder;
bool have_style = false;
bool have_order = false;
bool ok = true;
char *rawstring;
int *myextra;
char *result;
List *elemlist;
ListCell *l;
/* Need a modifiable copy of string */
rawstring = pstrdup(*newval);
/* Parse string into list of identifiers */
if (!SplitIdentifierString(rawstring, ',', &elemlist))
{
/* syntax error in list */
GUC_check_errdetail("List syntax is invalid.");
pfree(rawstring);
list_free(elemlist);
return false;
}
foreach(l, elemlist)
{
char *tok = (char *) lfirst(l);
/* Ugh. Somebody ought to write a table driven version -- mjl */
if (pg_strcasecmp(tok, "ISO") == 0)
{
if (have_style && newDateStyle != USE_ISO_DATES)
ok = false; /* conflicting styles */
newDateStyle = USE_ISO_DATES;
have_style = true;
}
else if (pg_strcasecmp(tok, "SQL") == 0)
{
if (have_style && newDateStyle != USE_SQL_DATES)
ok = false; /* conflicting styles */
newDateStyle = USE_SQL_DATES;
have_style = true;
}
else if (pg_strncasecmp(tok, "POSTGRES", 8) == 0)
{
if (have_style && newDateStyle != USE_POSTGRES_DATES)
ok = false; /* conflicting styles */
newDateStyle = USE_POSTGRES_DATES;
have_style = true;
}
else if (pg_strcasecmp(tok, "GERMAN") == 0)
{
if (have_style && newDateStyle != USE_GERMAN_DATES)
ok = false; /* conflicting styles */
newDateStyle = USE_GERMAN_DATES;
have_style = true;
/* GERMAN also sets DMY, unless explicitly overridden */
if (!have_order)
newDateOrder = DATEORDER_DMY;
}
else if (pg_strcasecmp(tok, "YMD") == 0)
{
if (have_order && newDateOrder != DATEORDER_YMD)
ok = false; /* conflicting orders */
newDateOrder = DATEORDER_YMD;
have_order = true;
}
else if (pg_strcasecmp(tok, "DMY") == 0 ||
pg_strncasecmp(tok, "EURO", 4) == 0)
{
if (have_order && newDateOrder != DATEORDER_DMY)
ok = false; /* conflicting orders */
newDateOrder = DATEORDER_DMY;
have_order = true;
}
else if (pg_strcasecmp(tok, "MDY") == 0 ||
pg_strcasecmp(tok, "US") == 0 ||
pg_strncasecmp(tok, "NONEURO", 7) == 0)
{
if (have_order && newDateOrder != DATEORDER_MDY)
ok = false; /* conflicting orders */
newDateOrder = DATEORDER_MDY;
have_order = true;
}
else if (pg_strcasecmp(tok, "DEFAULT") == 0)
{
/*
* Easiest way to get the current DEFAULT state is to fetch the
* DEFAULT string from guc.c and recursively parse it.
*
* We can't simply "return check_datestyle(...)" because we need
* to handle constructs like "DEFAULT, ISO".
*/
char *subval;
void *subextra = NULL;
subval = strdup(GetConfigOptionResetString("datestyle"));
if (!subval)
{
ok = false;
break;
}
if (!check_datestyle(&subval, &subextra, source))
{
free(subval);
ok = false;
break;
}
myextra = (int *) subextra;
if (!have_style)
newDateStyle = myextra[0];
if (!have_order)
newDateOrder = myextra[1];
free(subval);
free(subextra);
}
else
{
GUC_check_errdetail("Unrecognized key word: \"%s\".", tok);
pfree(rawstring);
list_free(elemlist);
return false;
}
}
pfree(rawstring);
list_free(elemlist);
if (!ok)
{
GUC_check_errdetail("Conflicting \"datestyle\" specifications.");
return false;
}
/*
* Prepare the canonical string to return. GUC wants it malloc'd.
*/
result = (char *) malloc(32);
if (!result)
return false;
switch (newDateStyle)
{
case USE_ISO_DATES:
strcpy(result, "ISO");
break;
case USE_SQL_DATES:
strcpy(result, "SQL");
break;
case USE_GERMAN_DATES:
strcpy(result, "German");
break;
default:
strcpy(result, "Postgres");
break;
}
switch (newDateOrder)
{
case DATEORDER_YMD:
strcat(result, ", YMD");
break;
case DATEORDER_DMY:
strcat(result, ", DMY");
break;
default:
strcat(result, ", MDY");
break;
}
free(*newval);
*newval = result;
/*
* Set up the "extra" struct actually used by assign_datestyle.
*/
myextra = (int *) malloc(2 * sizeof(int));
if (!myextra)
return false;
myextra[0] = newDateStyle;
myextra[1] = newDateOrder;
*extra = (void *) myextra;
return true;
}
/*
* assign_datestyle: GUC assign_hook for datestyle
*/
void
assign_datestyle(const char *newval, void *extra)
{
int *myextra = (int *) extra;
DateStyle = myextra[0];
DateOrder = myextra[1];
}
/*
* TIMEZONE
*/
/*
* check_timezone: GUC check_hook for timezone
*/
bool
check_timezone(char **newval, void **extra, GucSource source)
{
pg_tz *new_tz;
long gmtoffset;
char *endptr;
double hours;
if (pg_strncasecmp(*newval, "interval", 8) == 0)
{
/*
* Support INTERVAL 'foo'. This is for SQL spec compliance, not
* because it has any actual real-world usefulness.
*/
const char *valueptr = *newval;
char *val;
Interval *interval;
valueptr += 8;
while (isspace((unsigned char) *valueptr))
valueptr++;
if (*valueptr++ != '\'')
return false;
val = pstrdup(valueptr);
/* Check and remove trailing quote */
endptr = strchr(val, '\'');
if (!endptr || endptr[1] != '\0')
{
pfree(val);
return false;
}
*endptr = '\0';
/*
* Try to parse it. XXX an invalid interval format will result in
* ereport(ERROR), which is not desirable for GUC. We did what we
* could to guard against this in flatten_set_variable_args, but a
* string coming in from postgresql.conf might contain anything.
*/
interval = DatumGetIntervalP(DirectFunctionCall3(interval_in,
CStringGetDatum(val),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1)));
pfree(val);
if (interval->month != 0)
{
GUC_check_errdetail("Cannot specify months in time zone interval.");
pfree(interval);
return false;
}
if (interval->day != 0)
{
GUC_check_errdetail("Cannot specify days in time zone interval.");
pfree(interval);
return false;
}
/* Here we change from SQL to Unix sign convention */
gmtoffset = -(interval->time / USECS_PER_SEC);
new_tz = pg_tzset_offset(gmtoffset);
pfree(interval);
}
else
{
/*
* Try it as a numeric number of hours (possibly fractional).
*/
hours = strtod(*newval, &endptr);
if (endptr != *newval && *endptr == '\0')
{
/* Here we change from SQL to Unix sign convention */
gmtoffset = -hours * SECS_PER_HOUR;
new_tz = pg_tzset_offset(gmtoffset);
}
else
{
/*
* Otherwise assume it is a timezone name, and try to load it.
*/
new_tz = pg_tzset(*newval);
if (!new_tz)
{
/* Doesn't seem to be any great value in errdetail here */
return false;
}
if (!pg_tz_acceptable(new_tz))
{
GUC_check_errmsg("time zone \"%s\" appears to use leap seconds",
*newval);
GUC_check_errdetail("PostgreSQL does not support leap seconds.");
return false;
}
}
}
/* Test for failure in pg_tzset_offset, which we assume is out-of-range */
if (!new_tz)
{
GUC_check_errdetail("UTC timezone offset is out of range.");
return false;
}
/*
* Pass back data for assign_timezone to use
*/
*extra = malloc(sizeof(pg_tz *));
if (!*extra)
return false;
*((pg_tz **) *extra) = new_tz;
return true;
}
/*
* assign_timezone: GUC assign_hook for timezone
*/
void
assign_timezone(const char *newval, void *extra)
{
session_timezone = *((pg_tz **) extra);
}
/*
* show_timezone: GUC show_hook for timezone
*/
const char *
show_timezone(void)
{
const char *tzn;
/* Always show the zone's canonical name */
tzn = pg_get_timezone_name(session_timezone);
if (tzn != NULL)
return tzn;
return "unknown";
}
/*
* LOG_TIMEZONE
*
* For log_timezone, we don't support the interval-based methods of setting a
* zone, which are only there for SQL spec compliance not because they're
* actually useful.
*/
/*
* check_log_timezone: GUC check_hook for log_timezone
*/
bool
check_log_timezone(char **newval, void **extra, GucSource source)
{
pg_tz *new_tz;
/*
* Assume it is a timezone name, and try to load it.
*/
new_tz = pg_tzset(*newval);
if (!new_tz)
{
/* Doesn't seem to be any great value in errdetail here */
return false;
}
if (!pg_tz_acceptable(new_tz))
{
GUC_check_errmsg("time zone \"%s\" appears to use leap seconds",
*newval);
GUC_check_errdetail("PostgreSQL does not support leap seconds.");
return false;
}
/*
* Pass back data for assign_log_timezone to use
*/
*extra = malloc(sizeof(pg_tz *));
if (!*extra)
return false;
*((pg_tz **) *extra) = new_tz;
return true;
}
/*
* assign_log_timezone: GUC assign_hook for log_timezone
*/
void
assign_log_timezone(const char *newval, void *extra)
{
log_timezone = *((pg_tz **) extra);
}
/*
* show_log_timezone: GUC show_hook for log_timezone
*/
const char *
show_log_timezone(void)
{
const char *tzn;
/* Always show the zone's canonical name */
tzn = pg_get_timezone_name(log_timezone);
if (tzn != NULL)
return tzn;
return "unknown";
}
/*
* SET TRANSACTION READ ONLY and SET TRANSACTION READ WRITE
*
* We allow idempotent changes (r/w -> r/w and r/o -> r/o) at any time, and
* we also always allow changes from read-write to read-only. However,
* read-only may be changed to read-write only when in a top-level transaction
* that has not yet taken an initial snapshot. Can't do it in a hot standby,
* either.
*
* If we are not in a transaction at all, just allow the change; it means
* nothing since XactReadOnly will be reset by the next StartTransaction().
* The IsTransactionState() test protects us against trying to check
* RecoveryInProgress() in contexts where shared memory is not accessible.
* (Similarly, if we're restoring state in a parallel worker, just allow
* the change.)
*/
bool
check_transaction_read_only(bool *newval, void **extra, GucSource source)
{
if (*newval == false && XactReadOnly && IsTransactionState() && !InitializingParallelWorker)
{
/* Can't go to r/w mode inside a r/o transaction */
if (IsSubTransaction())
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("cannot set transaction read-write mode inside a read-only transaction");
return false;
}
/* Top level transaction can't change to r/w after first snapshot. */
if (FirstSnapshotSet)
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("transaction read-write mode must be set before any query");
return false;
}
/* Can't go to r/w mode while recovery is still active */
if (RecoveryInProgress())
{
GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
GUC_check_errmsg("cannot set transaction read-write mode during recovery");
return false;
}
}
return true;
}
/*
* SET TRANSACTION ISOLATION LEVEL
*
* We allow idempotent changes at any time, but otherwise this can only be
* changed in a toplevel transaction that has not yet taken a snapshot.
*
* As in check_transaction_read_only, allow it if not inside a transaction.
*/
bool
check_XactIsoLevel(int *newval, void **extra, GucSource source)
{
int newXactIsoLevel = *newval;
if (newXactIsoLevel != XactIsoLevel && IsTransactionState())
{
if (FirstSnapshotSet)
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("SET TRANSACTION ISOLATION LEVEL must be called before any query");
return false;
}
/* We ignore a subtransaction setting it to the existing value. */
if (IsSubTransaction())
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("SET TRANSACTION ISOLATION LEVEL must not be called in a subtransaction");
return false;
}
/* Can't go to serializable mode while recovery is still active */
if (newXactIsoLevel == XACT_SERIALIZABLE && RecoveryInProgress())
{
GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
GUC_check_errmsg("cannot use serializable mode in a hot standby");
GUC_check_errhint("You can use REPEATABLE READ instead.");
return false;
}
}
/*
* GPDB_91_MERGE_FIXME: Prior to PostgreSQL 9.1, serializable isolation was
* implemented as read committed. True serializable isolation level is
* supported as of PostgreSQL 9.1. However, Greenplum lacks the support to
* detect serialization conflicts using predicate locks at cluster level.
* Until that support is implemented, let's keep old behavior by falling
* back to repeatable read. Also, for similar reasons guc
* transaction_deferrable is not dispatched to QE's as no use
* currently. When serializable is fixed make sure to fix dispatching of the
* transaction_deferrable guc via DtxContextInfo similar to
* transaction_isolation.
*/
if (newXactIsoLevel == XACT_SERIALIZABLE)
{
elog(LOG, "serializable isolation requested, falling back to "
"repeatable read until serializable is supported in Greenplum");
*newval = XACT_REPEATABLE_READ;
}
return true;
}
bool
check_DefaultXactIsoLevel(int *newval, void **extra, GucSource source)
{
/*
* As the fixme in assign_XactIsoLevel, DefaultXactIsoLevel also need
* to fallback from 'serializable' to 'repeatable read'
*/
if (*newval == XACT_SERIALIZABLE)
{
elog(LOG, "default serializable isolation requested, falling back to "
"repeatable read until serializable is supported in Greenplum");
*newval = XACT_REPEATABLE_READ;
}
return true;
}
/*
* SET TRANSACTION [NOT] DEFERRABLE
*/
bool
check_transaction_deferrable(bool *newval, void **extra, GucSource source)
{
if (IsSubTransaction())
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("SET TRANSACTION [NOT] DEFERRABLE cannot be called within a subtransaction");
return false;
}
if (FirstSnapshotSet)
{
GUC_check_errcode(ERRCODE_ACTIVE_SQL_TRANSACTION);
GUC_check_errmsg("SET TRANSACTION [NOT] DEFERRABLE must be called before any query");
return false;
}
return true;
}
/*
* Random number seed
*
* We can't roll back the random sequence on error, and we don't want
* config file reloads to affect it, so we only want interactive SET SEED
* commands to set it. We use the "extra" storage to ensure that rollbacks
* don't try to do the operation again.
*/
bool
check_random_seed(double *newval, void **extra, GucSource source)
{
*extra = malloc(sizeof(int));
if (!*extra)
return false;
/* Arm the assign only if source of value is an interactive SET */
*((int *) *extra) = (source >= PGC_S_INTERACTIVE);
return true;
}
void
assign_random_seed(double newval, void *extra)
{
/* We'll do this at most once for any setting of the GUC variable */
if (*((int *) extra))
DirectFunctionCall1(setseed, Float8GetDatum(newval));
*((int *) extra) = 0;
}
const char *
show_random_seed(void)
{
return "unavailable";
}
/*
* SET CLIENT_ENCODING
*/
bool
check_client_encoding(char **newval, void **extra, GucSource source)
{
int encoding;
const char *canonical_name;
/* Look up the encoding by name */
encoding = pg_valid_client_encoding(*newval);
if (encoding < 0)
return false;
/* Get the canonical name (no aliases, uniform case) */
canonical_name = pg_encoding_to_char(encoding);
/*
* If we are not within a transaction then PrepareClientEncoding will not
* be able to look up the necessary conversion procs. If we are still
* starting up, it will return "OK" anyway, and InitializeClientEncoding
* will fix things once initialization is far enough along. After
* startup, we'll fail. This would only happen if someone tries to change
* client_encoding in postgresql.conf and then SIGHUP existing sessions.
* It seems like a bad idea for client_encoding to change that way anyhow,
* so we don't go out of our way to support it.
*
* Note: in the postmaster, or any other process that never calls
* InitializeClientEncoding, PrepareClientEncoding will always succeed,
* and so will SetClientEncoding; but they won't do anything, which is OK.
*/
if (PrepareClientEncoding(encoding) < 0)
{
if (IsTransactionState())
{
/* Must be a genuine no-such-conversion problem */
GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
GUC_check_errdetail("Conversion between %s and %s is not supported.",
canonical_name,
GetDatabaseEncodingName());
}
else
{
/* Provide a useful complaint */
GUC_check_errdetail("Cannot change \"client_encoding\" now.");
}
return false;
}
/*
* Replace the user-supplied string with the encoding's canonical name.
* This gets rid of aliases and case-folding variations.
*
* XXX Although canonicalizing seems like a good idea in the abstract, it
* breaks pre-9.1 JDBC drivers, which expect that if they send "UNICODE"
* as the client_encoding setting then it will read back the same way. As
* a workaround, don't replace the string if it's "UNICODE". Remove that
* hack when pre-9.1 JDBC drivers are no longer in use.
*/
if (strcmp(*newval, canonical_name) != 0 &&
strcmp(*newval, "UNICODE") != 0)
{
free(*newval);
*newval = strdup(canonical_name);
if (!*newval)
return false;
}
/*
* Save the encoding's ID in *extra, for use by assign_client_encoding.
*/
*extra = malloc(sizeof(int));
if (!*extra)
return false;
*((int *) *extra) = encoding;
return true;
}
void
assign_client_encoding(const char *newval, void *extra)
{
int encoding = *((int *) extra);
/*
* Parallel workers send data to the leader, not the client. They always
* send data using the database encoding.
*/
if (IsParallelWorker())
{
/*
* During parallel worker startup, we want to accept the leader's
* client_encoding setting so that anyone who looks at the value in
* the worker sees the same value that they would see in the leader.
*/
if (InitializingParallelWorker)
return;
/*
* A change other than during startup, for example due to a SET clause
* attached to a function definition, should be rejected, as there is
* nothing we can do inside the worker to make it take effect.
*/
ereport(ERROR,
(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
errmsg("cannot change client_encoding during a parallel operation")));
}
/* We do not expect an error if PrepareClientEncoding succeeded */
if (SetClientEncoding(encoding) < 0)
elog(LOG, "SetClientEncoding(%d) failed", encoding);
}
/*
* SET SESSION AUTHORIZATION
*/
typedef struct
{
/* This is the "extra" state for both SESSION AUTHORIZATION and ROLE */
Oid roleid;
bool is_superuser;
} role_auth_extra;
bool
check_session_authorization(char **newval, void **extra, GucSource source)
{
HeapTuple roleTup;
Form_pg_authid roleform;
Oid roleid;
bool is_superuser;
role_auth_extra *myextra;
/* Do nothing for the boot_val default of NULL */
if (*newval == NULL)
return true;
if (!IsTransactionState())
{
/*
* Can't do catalog lookups, so fail. The result of this is that
* session_authorization cannot be set in postgresql.conf, which seems
* like a good thing anyway, so we don't work hard to avoid it.
*/
return false;
}
/* Look up the username */
roleTup = SearchSysCache1(AUTHNAME, PointerGetDatum(*newval));
if (!HeapTupleIsValid(roleTup))
{
GUC_check_errmsg("role \"%s\" does not exist", *newval);
return false;
}
roleform = (Form_pg_authid) GETSTRUCT(roleTup);
roleid = roleform->oid;
is_superuser = roleform->rolsuper;
ReleaseSysCache(roleTup);
/* Set up "extra" struct for assign_session_authorization to use */
myextra = (role_auth_extra *) malloc(sizeof(role_auth_extra));
if (!myextra)
return false;
myextra->roleid = roleid;
myextra->is_superuser = is_superuser;
*extra = (void *) myextra;
return true;
}
void
assign_session_authorization(const char *newval, void *extra)
{
role_auth_extra *myextra = (role_auth_extra *) extra;
/* Do nothing for the boot_val default of NULL */
if (!myextra)
return;
SetSessionAuthorization(myextra->roleid, myextra->is_superuser);
}
/*
* SET ROLE
*
* The SQL spec requires "SET ROLE NONE" to unset the role, so we hardwire
* a translation of "none" to InvalidOid. Otherwise this is much like
* SET SESSION AUTHORIZATION.
*/
extern char *role_string; /* in guc.c */
bool
check_role(char **newval, void **extra, GucSource source)
{
HeapTuple roleTup;
Oid roleid;
bool is_superuser;
role_auth_extra *myextra;
Form_pg_authid roleform;
if (strcmp(*newval, "none") == 0)
{
/* hardwired translation */
roleid = InvalidOid;
is_superuser = false;
}
else
{
if (!IsTransactionState())
{
/*
* Can't do catalog lookups, so fail. The result of this is that
* role cannot be set in postgresql.conf, which seems like a good
* thing anyway, so we don't work hard to avoid it.
*/
return false;
}
/* Look up the username */
roleTup = SearchSysCache1(AUTHNAME, PointerGetDatum(*newval));
if (!HeapTupleIsValid(roleTup))
{
GUC_check_errmsg("role \"%s\" does not exist", *newval);
return false;
}
roleform = (Form_pg_authid) GETSTRUCT(roleTup);
roleid = roleform->oid;
is_superuser = roleform->rolsuper;
ReleaseSysCache(roleTup);
/*
* Verify that session user is allowed to become this role, but skip
* this in parallel mode, where we must blindly recreate the parallel
* leader's state.
*/
if (!InitializingParallelWorker &&
!is_member_of_role(GetSessionUserId(), roleid))
{
GUC_check_errcode(ERRCODE_INSUFFICIENT_PRIVILEGE);
GUC_check_errmsg("permission denied to set role \"%s\"",
*newval);
return false;
}
}
/* Set up "extra" struct for assign_role to use */
myextra = (role_auth_extra *) malloc(sizeof(role_auth_extra));
if (!myextra)
return false;
myextra->roleid = roleid;
myextra->is_superuser = is_superuser;
*extra = (void *) myextra;
return true;
}
void
assign_role(const char *newval, void *extra)
{
role_auth_extra *myextra = (role_auth_extra *) extra;
SetCurrentRoleId(myextra->roleid, myextra->is_superuser);
}
const char *
show_role(void)
{
/*
* Check whether SET ROLE is active; if not return "none". This is a
* kluge to deal with the fact that SET SESSION AUTHORIZATION logically
* resets SET ROLE to NONE, but we cannot set the GUC role variable from
* assign_session_authorization (because we haven't got enough info to
* call set_config_option).
*/
if (!OidIsValid(GetCurrentRoleId()))
return "none";
/* Otherwise we can just use the GUC string */
return role_string ? role_string : "none";
}
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