xlogfuncs.c File Reference

#include "postgres.h"
#include "access/htup_details.h"
#include "access/xlog.h"
#include "access/xlog_internal.h"
#include "access/xlogutils.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "replication/walreceiver.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#include "utils/numeric.h"
#include "utils/guc.h"
#include "utils/pg_lsn.h"
#include "utils/timestamp.h"
#include "utils/tuplestore.h"
#include "storage/fd.h"
#include "storage/ipc.h"

Include dependency graph for xlogfuncs.c:

Go to the source code of this file.

Functions
static void	nonexclusive_base_backup_cleanup (int code, Datum arg)
Datum	pg_start_backup (PG_FUNCTION_ARGS)
Datum	pg_stop_backup (PG_FUNCTION_ARGS)
Datum	pg_stop_backup_v2 (PG_FUNCTION_ARGS)
Datum	pg_switch_wal (PG_FUNCTION_ARGS)
Datum	pg_create_restore_point (PG_FUNCTION_ARGS)
Datum	pg_current_wal_lsn (PG_FUNCTION_ARGS)
Datum	pg_current_wal_insert_lsn (PG_FUNCTION_ARGS)
Datum	pg_current_wal_flush_lsn (PG_FUNCTION_ARGS)
Datum	pg_last_wal_receive_lsn (PG_FUNCTION_ARGS)
Datum	pg_last_wal_replay_lsn (PG_FUNCTION_ARGS)
Datum	pg_walfile_name_offset (PG_FUNCTION_ARGS)
Datum	pg_walfile_name (PG_FUNCTION_ARGS)
Datum	pg_wal_replay_pause (PG_FUNCTION_ARGS)
Datum	pg_wal_replay_resume (PG_FUNCTION_ARGS)
Datum	pg_is_wal_replay_paused (PG_FUNCTION_ARGS)
Datum	pg_last_xact_replay_timestamp (PG_FUNCTION_ARGS)
Datum	pg_is_in_recovery (PG_FUNCTION_ARGS)
Datum	pg_wal_lsn_diff (PG_FUNCTION_ARGS)
Datum	pg_is_in_backup (PG_FUNCTION_ARGS)
Datum	pg_backup_start_time (PG_FUNCTION_ARGS)

Variables
static StringInfo	label_file
static StringInfo	tblspc_map_file

Function Documentation

nonexclusive_base_backup_cleanup()

static void nonexclusive_base_backup_cleanup ( int  code, Datum  arg  )

static

Definition at line 50 of file xlogfuncs.c.

References do_pg_abort_backup(), ereport, errmsg(), and WARNING.

Referenced by pg_start_backup(), and pg_stop_backup_v2().

{
    do_pg_abort_backup();
    ereport(WARNING,
            (errmsg("aborting backup due to backend exiting before pg_stop_backup was called")));
}

pg_backup_start_time()

Datum pg_backup_start_time

(

PG_FUNCTION_ARGS

)

Definition at line 642 of file xlogfuncs.c.

References AllocateFile(), BACKUP_LABEL_FILE, CStringGetDatum, DirectFunctionCall3, ereport, errcode(), errcode_for_file_access(), errmsg(), ERROR, FreeFile(), Int32GetDatum, InvalidOid, MAXPGPATH, ObjectIdGetDatum, PG_RETURN_DATUM, PG_RETURN_NULL, and timestamptz_in().

{
    Datum       xtime;
    FILE       *lfp;
    char        fline[MAXPGPATH];
    char        backup_start_time[30];

    /*
     * See if label file is present
     */
    lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
    if (lfp == NULL)
    {
        if (errno != ENOENT)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not read file \"%s\": %m",
                            BACKUP_LABEL_FILE)));
        PG_RETURN_NULL();
    }

    /*
     * Parse the file to find the START TIME line.
     */
    backup_start_time[0] = '\0';
    while (fgets(fline, sizeof(fline), lfp) != NULL)
    {
        if (sscanf(fline, "START TIME: %25[^\n]\n", backup_start_time) == 1)
            break;
    }

    /* Check for a read error. */
    if (ferror(lfp))
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE)));

    /* Close the backup label file. */
    if (FreeFile(lfp))
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not close file \"%s\": %m", BACKUP_LABEL_FILE)));

    if (strlen(backup_start_time) == 0)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));

    /*
     * Convert the time string read from file to TimestampTz form.
     */
    xtime = DirectFunctionCall3(timestamptz_in,
                                CStringGetDatum(backup_start_time),
                                ObjectIdGetDatum(InvalidOid),
                                Int32GetDatum(-1));

    PG_RETURN_DATUM(xtime);
}

pg_create_restore_point()

Datum pg_create_restore_point

(

PG_FUNCTION_ARGS

)

Definition at line 304 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, MAXFNAMELEN, PG_GETARG_TEXT_PP, PG_RETURN_LSN, RecoveryInProgress(), text_to_cstring(), XLogIsNeeded, and XLogRestorePoint().

{
    text       *restore_name = PG_GETARG_TEXT_PP(0);
    char       *restore_name_str;
    XLogRecPtr  restorepoint;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 (errmsg("recovery is in progress"),
                  errhint("WAL control functions cannot be executed during recovery."))));

    if (!XLogIsNeeded())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("WAL level not sufficient for creating a restore point"),
                 errhint("wal_level must be set to \"replica\" or \"logical\" at server start.")));

    restore_name_str = text_to_cstring(restore_name);

    if (strlen(restore_name_str) >= MAXFNAMELEN)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("value too long for restore point (maximum %d characters)", MAXFNAMELEN - 1)));

    restorepoint = XLogRestorePoint(restore_name_str);

    /*
     * As a convenience, return the WAL location of the restore point record
     */
    PG_RETURN_LSN(restorepoint);
}

pg_current_wal_flush_lsn()

Datum pg_current_wal_flush_lsn

(

PG_FUNCTION_ARGS

)

Definition at line 387 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, GetFlushRecPtr(), PG_RETURN_LSN, and RecoveryInProgress().

{
    XLogRecPtr  current_recptr;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("WAL control functions cannot be executed during recovery.")));

    current_recptr = GetFlushRecPtr();

    PG_RETURN_LSN(current_recptr);
}

pg_current_wal_insert_lsn()

Datum pg_current_wal_insert_lsn

(

PG_FUNCTION_ARGS

)

Definition at line 366 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, GetXLogInsertRecPtr(), PG_RETURN_LSN, and RecoveryInProgress().

{
    XLogRecPtr  current_recptr;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("WAL control functions cannot be executed during recovery.")));

    current_recptr = GetXLogInsertRecPtr();

    PG_RETURN_LSN(current_recptr);
}

pg_current_wal_lsn()

Datum pg_current_wal_lsn

(

PG_FUNCTION_ARGS

)

Definition at line 345 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, GetXLogWriteRecPtr(), PG_RETURN_LSN, and RecoveryInProgress().

{
    XLogRecPtr  current_recptr;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("WAL control functions cannot be executed during recovery.")));

    current_recptr = GetXLogWriteRecPtr();

    PG_RETURN_LSN(current_recptr);
}

pg_is_in_backup()

Datum pg_is_in_backup

(

PG_FUNCTION_ARGS

)

Definition at line 630 of file xlogfuncs.c.

References BackupInProgress(), and PG_RETURN_BOOL.

{
    PG_RETURN_BOOL(BackupInProgress());
}

pg_is_in_recovery()

Datum pg_is_in_recovery

(

PG_FUNCTION_ARGS

)

Definition at line 606 of file xlogfuncs.c.

References PG_RETURN_BOOL, and RecoveryInProgress().

{
    PG_RETURN_BOOL(RecoveryInProgress());
}

pg_is_wal_replay_paused()

Datum pg_is_wal_replay_paused

(

PG_FUNCTION_ARGS

)

Definition at line 573 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, PG_RETURN_BOOL, RecoveryInProgress(), and RecoveryIsPaused().

{
    if (!RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is not in progress"),
                 errhint("Recovery control functions can only be executed during recovery.")));

    PG_RETURN_BOOL(RecoveryIsPaused());
}

pg_last_wal_receive_lsn()

Datum pg_last_wal_receive_lsn

(

PG_FUNCTION_ARGS

)

Definition at line 409 of file xlogfuncs.c.

References GetWalRcvWriteRecPtr(), PG_RETURN_LSN, and PG_RETURN_NULL.

{
    XLogRecPtr  recptr;

    recptr = GetWalRcvWriteRecPtr(NULL, NULL);

    if (recptr == 0)
        PG_RETURN_NULL();

    PG_RETURN_LSN(recptr);
}

pg_last_wal_replay_lsn()

Datum pg_last_wal_replay_lsn

(

PG_FUNCTION_ARGS

)

Definition at line 428 of file xlogfuncs.c.

References GetXLogReplayRecPtr(), PG_RETURN_LSN, and PG_RETURN_NULL.

{
    XLogRecPtr  recptr;

    recptr = GetXLogReplayRecPtr(NULL);

    if (recptr == 0)
        PG_RETURN_NULL();

    PG_RETURN_LSN(recptr);
}

pg_last_xact_replay_timestamp()

Datum pg_last_xact_replay_timestamp

(

PG_FUNCTION_ARGS

)

Definition at line 591 of file xlogfuncs.c.

References GetLatestXTime(), PG_RETURN_NULL, and PG_RETURN_TIMESTAMPTZ.

{
    TimestampTz xtime;

    xtime = GetLatestXTime();
    if (xtime == 0)
        PG_RETURN_NULL();

    PG_RETURN_TIMESTAMPTZ(xtime);
}

pg_start_backup()

Datum pg_start_backup

(

PG_FUNCTION_ARGS

)

Definition at line 70 of file xlogfuncs.c.

References before_shmem_exit(), do_pg_start_backup(), ereport, errcode(), errmsg(), ERROR, get_backup_status(), makeStringInfo(), MemoryContextSwitchTo(), nonexclusive_base_backup_cleanup(), PG_GETARG_BOOL, PG_GETARG_TEXT_PP, PG_RETURN_LSN, SESSION_BACKUP_NON_EXCLUSIVE, status(), text_to_cstring(), and TopMemoryContext.

{
    text       *backupid = PG_GETARG_TEXT_PP(0);
    bool        fast = PG_GETARG_BOOL(1);
    bool        exclusive = PG_GETARG_BOOL(2);
    char       *backupidstr;
    XLogRecPtr  startpoint;
    SessionBackupState status = get_backup_status();

    backupidstr = text_to_cstring(backupid);

    if (status == SESSION_BACKUP_NON_EXCLUSIVE)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("a backup is already in progress in this session")));

    if (exclusive)
    {
        startpoint = do_pg_start_backup(backupidstr, fast, NULL, NULL,
                                        NULL, NULL, false, true);
    }
    else
    {
        MemoryContext oldcontext;

        /*
         * Label file and tablespace map file need to be long-lived, since
         * they are read in pg_stop_backup.
         */
        oldcontext = MemoryContextSwitchTo(TopMemoryContext);
        label_file = makeStringInfo();
        tblspc_map_file = makeStringInfo();
        MemoryContextSwitchTo(oldcontext);

        startpoint = do_pg_start_backup(backupidstr, fast, NULL, label_file,
                                        NULL, tblspc_map_file, false, true);

        before_shmem_exit(nonexclusive_base_backup_cleanup, (Datum) 0);
    }

    PG_RETURN_LSN(startpoint);
}

pg_stop_backup()

Datum pg_stop_backup

(

PG_FUNCTION_ARGS

)

Definition at line 134 of file xlogfuncs.c.

References do_pg_stop_backup(), ereport, errcode(), errhint(), errmsg(), ERROR, get_backup_status(), PG_RETURN_LSN, SESSION_BACKUP_NON_EXCLUSIVE, and status().

{
    XLogRecPtr  stoppoint;
    SessionBackupState status = get_backup_status();

    if (status == SESSION_BACKUP_NON_EXCLUSIVE)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("non-exclusive backup in progress"),
                 errhint("Did you mean to use pg_stop_backup('f')?")));

    /*
     * Exclusive backups were typically started in a different connection, so
     * don't try to verify that status of backup is set to
     * SESSION_BACKUP_EXCLUSIVE in this function. Actual verification that an
     * exclusive backup is in fact running is handled inside
     * do_pg_stop_backup.
     */
    stoppoint = do_pg_stop_backup(NULL, true, NULL);

    PG_RETURN_LSN(stoppoint);
}

pg_stop_backup_v2()

Datum pg_stop_backup_v2

(

PG_FUNCTION_ARGS

)

Definition at line 176 of file xlogfuncs.c.

References ReturnSetInfo::allowedModes, cancel_before_shmem_exit(), CStringGetTextDatum, StringInfoData::data, do_pg_stop_backup(), ReturnSetInfo::econtext, ExprContext::ecxt_per_query_memory, elog, ereport, errcode(), errhint(), errmsg(), ERROR, get_backup_status(), get_call_result_type(), IsA, LSNGetDatum, MemoryContextSwitchTo(), MemSet, nonexclusive_base_backup_cleanup(), pfree(), PG_GETARG_BOOL, ReturnSetInfo::returnMode, SESSION_BACKUP_NON_EXCLUSIVE, ReturnSetInfo::setDesc, ReturnSetInfo::setResult, SFRM_Materialize, status(), tuplestore_begin_heap(), tuplestore_donestoring, tuplestore_putvalues(), TYPEFUNC_COMPOSITE, values, and work_mem.

{
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    MemoryContext per_query_ctx;
    MemoryContext oldcontext;
    Datum       values[3];
    bool        nulls[3];

    bool        exclusive = PG_GETARG_BOOL(0);
    bool        waitforarchive = PG_GETARG_BOOL(1);
    XLogRecPtr  stoppoint;
    SessionBackupState status = get_backup_status();

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("materialize mode required, but it is not " \
                        "allowed in this context")));

    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
    oldcontext = MemoryContextSwitchTo(per_query_ctx);

    tupstore = tuplestore_begin_heap(true, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;

    MemoryContextSwitchTo(oldcontext);

    MemSet(values, 0, sizeof(values));
    MemSet(nulls, 0, sizeof(nulls));

    if (exclusive)
    {
        if (status == SESSION_BACKUP_NON_EXCLUSIVE)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("non-exclusive backup in progress"),
                     errhint("Did you mean to use pg_stop_backup('f')?")));

        /*
         * Stop the exclusive backup, and since we're in an exclusive backup
         * return NULL for both backup_label and tablespace_map.
         */
        stoppoint = do_pg_stop_backup(NULL, waitforarchive, NULL);

        nulls[1] = true;
        nulls[2] = true;
    }
    else
    {
        if (status != SESSION_BACKUP_NON_EXCLUSIVE)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("non-exclusive backup is not in progress"),
                     errhint("Did you mean to use pg_stop_backup('t')?")));

        /*
         * Stop the non-exclusive backup. Return a copy of the backup label
         * and tablespace map so they can be written to disk by the caller.
         */
        stoppoint = do_pg_stop_backup(label_file->data, waitforarchive, NULL);
        cancel_before_shmem_exit(nonexclusive_base_backup_cleanup, (Datum) 0);

        values[1] = CStringGetTextDatum(label_file->data);
        values[2] = CStringGetTextDatum(tblspc_map_file->data);

        /* Free structures allocated in TopMemoryContext */
        pfree(label_file->data);
        pfree(label_file);
        label_file = NULL;
        pfree(tblspc_map_file->data);
        pfree(tblspc_map_file);
        tblspc_map_file = NULL;
    }

    /* Stoppoint is included on both exclusive and nonexclusive backups */
    values[0] = LSNGetDatum(stoppoint);

    tuplestore_putvalues(tupstore, tupdesc, values, nulls);
    tuplestore_donestoring(typstore);

    return (Datum) 0;
}

pg_switch_wal()

Datum pg_switch_wal

(

PG_FUNCTION_ARGS

)

Definition at line 279 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, PG_RETURN_LSN, RecoveryInProgress(), and RequestXLogSwitch().

{
    XLogRecPtr  switchpoint;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("WAL control functions cannot be executed during recovery.")));

    switchpoint = RequestXLogSwitch(false);

    /*
     * As a convenience, return the WAL location of the switch record
     */
    PG_RETURN_LSN(switchpoint);
}

pg_wal_lsn_diff()

Datum pg_wal_lsn_diff

(

PG_FUNCTION_ARGS

)

Definition at line 615 of file xlogfuncs.c.

References DirectFunctionCall2, PG_GETARG_DATUM, pg_lsn_mi(), and PG_RETURN_NUMERIC.

{
    Datum       result;

    result = DirectFunctionCall2(pg_lsn_mi,
                                 PG_GETARG_DATUM(0),
                                 PG_GETARG_DATUM(1));

    PG_RETURN_NUMERIC(result);
}

pg_wal_replay_pause()

Datum pg_wal_replay_pause

(

PG_FUNCTION_ARGS

)

Definition at line 536 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, PG_RETURN_VOID, RecoveryInProgress(), and SetRecoveryPause().

{
    if (!RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is not in progress"),
                 errhint("Recovery control functions can only be executed during recovery.")));

    SetRecoveryPause(true);

    PG_RETURN_VOID();
}

pg_wal_replay_resume()

Datum pg_wal_replay_resume

(

PG_FUNCTION_ARGS

)

Definition at line 556 of file xlogfuncs.c.

References ereport, errcode(), errhint(), errmsg(), ERROR, PG_RETURN_VOID, RecoveryInProgress(), and SetRecoveryPause().

{
    if (!RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is not in progress"),
                 errhint("Recovery control functions can only be executed during recovery.")));

    SetRecoveryPause(false);

    PG_RETURN_VOID();
}

pg_walfile_name()

Datum pg_walfile_name

(

PG_FUNCTION_ARGS

)

Definition at line 511 of file xlogfuncs.c.

References cstring_to_text(), ereport, errcode(), errhint(), errmsg(), ERROR, MAXFNAMELEN, PG_GETARG_LSN, PG_RETURN_TEXT_P, RecoveryInProgress(), ThisTimeLineID, wal_segment_size, XLByteToPrevSeg, and XLogFileName.

{
    XLogSegNo   xlogsegno;
    XLogRecPtr  locationpoint = PG_GETARG_LSN(0);
    char        xlogfilename[MAXFNAMELEN];

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("pg_walfile_name() cannot be executed during recovery.")));

    XLByteToPrevSeg(locationpoint, xlogsegno, wal_segment_size);
    XLogFileName(xlogfilename, ThisTimeLineID, xlogsegno, wal_segment_size);

    PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
}

pg_walfile_name_offset()

Datum pg_walfile_name_offset

(

PG_FUNCTION_ARGS

)

Definition at line 449 of file xlogfuncs.c.

References BlessTupleDesc(), CreateTemplateTupleDesc(), CStringGetTextDatum, ereport, errcode(), errhint(), errmsg(), ERROR, heap_form_tuple(), HeapTupleGetDatum, MAXFNAMELEN, PG_GETARG_LSN, PG_RETURN_DATUM, RecoveryInProgress(), ThisTimeLineID, TupleDescInitEntry(), UInt32GetDatum, values, wal_segment_size, XLByteToPrevSeg, XLogFileName, and XLogSegmentOffset.

{
    XLogSegNo   xlogsegno;
    uint32      xrecoff;
    XLogRecPtr  locationpoint = PG_GETARG_LSN(0);
    char        xlogfilename[MAXFNAMELEN];
    Datum       values[2];
    bool        isnull[2];
    TupleDesc   resultTupleDesc;
    HeapTuple   resultHeapTuple;
    Datum       result;

    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("pg_walfile_name_offset() cannot be executed during recovery.")));

    /*
     * Construct a tuple descriptor for the result row.  This must match this
     * function's pg_proc entry!
     */
    resultTupleDesc = CreateTemplateTupleDesc(2, false);
    TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "file_name",
                       TEXTOID, -1, 0);
    TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "file_offset",
                       INT4OID, -1, 0);

    resultTupleDesc = BlessTupleDesc(resultTupleDesc);

    /*
     * xlogfilename
     */
    XLByteToPrevSeg(locationpoint, xlogsegno, wal_segment_size);
    XLogFileName(xlogfilename, ThisTimeLineID, xlogsegno, wal_segment_size);

    values[0] = CStringGetTextDatum(xlogfilename);
    isnull[0] = false;

    /*
     * offset
     */
    xrecoff = XLogSegmentOffset(locationpoint, wal_segment_size);

    values[1] = UInt32GetDatum(xrecoff);
    isnull[1] = false;

    /*
     * Tuple jam: Having first prepared your Datums, then squash together
     */
    resultHeapTuple = heap_form_tuple(resultTupleDesc, values, isnull);

    result = HeapTupleGetDatum(resultHeapTuple);

    PG_RETURN_DATUM(result);
}

Variable Documentation

label_file

StringInfo label_file

static

Definition at line 42 of file xlogfuncs.c.

tblspc_map_file

StringInfo tblspc_map_file

static

Definition at line 43 of file xlogfuncs.c.

Referenced by perform_base_backup().