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rawpage.c File Reference

#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "utils/builtins.h"
#include "utils/rel.h"
Include dependency graph for rawpage.c:

Go to the source code of this file.


Datum get_raw_page (PG_FUNCTION_ARGS)
Datum get_raw_page_fork (PG_FUNCTION_ARGS)
Datum page_header (PG_FUNCTION_ARGS)
static byteaget_raw_page_internal (text *relname, ForkNumber forknum, BlockNumber blkno)
 PG_FUNCTION_INFO_V1 (get_raw_page)
 PG_FUNCTION_INFO_V1 (get_raw_page_fork)
 PG_FUNCTION_INFO_V1 (page_header)



Function Documentation

Datum get_raw_page ( PG_FUNCTION_ARGS   ) 

Definition at line 45 of file rawpage.c.

References ereport, errhint(), errmsg(), ERROR, get_raw_page_internal(), MAIN_FORKNUM, PG_GETARG_TEXT_P, PG_GETARG_UINT32, PG_NARGS, and PG_RETURN_BYTEA_P.

    text       *relname = PG_GETARG_TEXT_P(0);
    uint32      blkno = PG_GETARG_UINT32(1);
    bytea      *raw_page;

     * We don't normally bother to check the number of arguments to a C
     * function, but here it's needed for safety because early 8.4 beta
     * releases mistakenly redefined get_raw_page() as taking three arguments.
    if (PG_NARGS() != 2)
                (errmsg("wrong number of arguments to get_raw_page()"),
                 errhint("Run the updated pageinspect.sql script.")));

    raw_page = get_raw_page_internal(relname, MAIN_FORKNUM, blkno);


Datum get_raw_page_fork ( PG_FUNCTION_ARGS   ) 

Definition at line 74 of file rawpage.c.

References forkname_to_number(), get_raw_page_internal(), PG_GETARG_TEXT_P, PG_GETARG_UINT32, PG_RETURN_BYTEA_P, and text_to_cstring().

    text       *relname = PG_GETARG_TEXT_P(0);
    text       *forkname = PG_GETARG_TEXT_P(1);
    uint32      blkno = PG_GETARG_UINT32(2);
    bytea      *raw_page;
    ForkNumber  forknum;

    forknum = forkname_to_number(text_to_cstring(forkname));

    raw_page = get_raw_page_internal(relname, forknum, blkno);


static bytea * get_raw_page_internal ( text relname,
ForkNumber  forknum,
BlockNumber  blkno 
) [static]

Definition at line 93 of file rawpage.c.

References AccessShareLock, buf, BUFFER_LOCK_SHARE, BUFFER_LOCK_UNLOCK, BufferGetPage, elog, ereport, errcode(), errmsg(), ERROR, LockBuffer(), makeRangeVarFromNameList(), NULL, palloc(), RBM_NORMAL, RelationData::rd_rel, ReadBufferExtended(), relation_close(), RELATION_IS_OTHER_TEMP, relation_openrv(), RelationGetNumberOfBlocks, RelationGetRelationName, ReleaseBuffer(), RELKIND_COMPOSITE_TYPE, RELKIND_FOREIGN_TABLE, RELKIND_VIEW, SET_VARSIZE, superuser(), textToQualifiedNameList(), VARDATA, and VARHDRSZ.

Referenced by get_raw_page(), and get_raw_page_fork().

    bytea      *raw_page;
    RangeVar   *relrv;
    Relation    rel;
    char       *raw_page_data;
    Buffer      buf;

    if (!superuser())
                 (errmsg("must be superuser to use raw functions"))));

    relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
    rel = relation_openrv(relrv, AccessShareLock);

    /* Check that this relation has storage */
    if (rel->rd_rel->relkind == RELKIND_VIEW)
                 errmsg("cannot get raw page from view \"%s\"",
    if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
                 errmsg("cannot get raw page from composite type \"%s\"",
    if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
                 errmsg("cannot get raw page from foreign table \"%s\"",

     * Reject attempts to read non-local temporary relations; we would be
     * likely to get wrong data since we have no visibility into the owning
     * session's local buffers.
                 errmsg("cannot access temporary tables of other sessions")));

    if (blkno >= RelationGetNumberOfBlocks(rel))
        elog(ERROR, "block number %u is out of range for relation \"%s\"",
             blkno, RelationGetRelationName(rel));

    /* Initialize buffer to copy to */
    raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ);
    raw_page_data = VARDATA(raw_page);

    /* Take a verbatim copy of the page */

    buf = ReadBufferExtended(rel, forknum, blkno, RBM_NORMAL, NULL);
    LockBuffer(buf, BUFFER_LOCK_SHARE);

    memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ);

    LockBuffer(buf, BUFFER_LOCK_UNLOCK);

    relation_close(rel, AccessShareLock);

    return raw_page;

Datum page_header ( PG_FUNCTION_ARGS   ) 

Definition at line 169 of file rawpage.c.

References CStringGetTextDatum, elog, ereport, errcode(), errmsg(), ERROR, get_call_result_type(), heap_form_tuple(), HeapTupleGetDatum, NULL, PageGetLSN, PageGetPageLayoutVersion, PageGetPageSize, PageHeaderData::pd_checksum, PageHeaderData::pd_flags, PageHeaderData::pd_lower, PageHeaderData::pd_prune_xid, PageHeaderData::pd_special, PageHeaderData::pd_upper, PG_GETARG_BYTEA_P, PG_RETURN_DATUM, snprintf(), superuser(), TransactionIdGetDatum, UInt16GetDatum, values, VARDATA, and VARSIZE.

    bytea      *raw_page = PG_GETARG_BYTEA_P(0);
    int         raw_page_size;

    TupleDesc   tupdesc;

    Datum       result;
    HeapTuple   tuple;
    Datum       values[9];
    bool        nulls[9];

    PageHeader  page;
    XLogRecPtr  lsn;
    char        lsnchar[64];

    if (!superuser())
                 (errmsg("must be superuser to use raw page functions"))));

    raw_page_size = VARSIZE(raw_page) - VARHDRSZ;

     * Check that enough data was supplied, so that we don't try to access
     * fields outside the supplied buffer.
    if (raw_page_size < sizeof(PageHeaderData))
                 errmsg("input page too small (%d bytes)", raw_page_size)));

    page = (PageHeader) VARDATA(raw_page);

    /* 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");

    /* Extract information from the page header */

    lsn = PageGetLSN(page);
    snprintf(lsnchar, sizeof(lsnchar), "%X/%X",
             (uint32) (lsn >> 32), (uint32) lsn);

    values[0] = CStringGetTextDatum(lsnchar);
    values[1] = UInt16GetDatum(page->pd_checksum);
    values[2] = UInt16GetDatum(page->pd_flags);
    values[3] = UInt16GetDatum(page->pd_lower);
    values[4] = UInt16GetDatum(page->pd_upper);
    values[5] = UInt16GetDatum(page->pd_special);
    values[6] = UInt16GetDatum(PageGetPageSize(page));
    values[7] = UInt16GetDatum(PageGetPageLayoutVersion(page));
    values[8] = TransactionIdGetDatum(page->pd_prune_xid);

    /* Build and return the tuple. */

    memset(nulls, 0, sizeof(nulls));

    tuple = heap_form_tuple(tupdesc, values, nulls);
    result = HeapTupleGetDatum(tuple);


PG_FUNCTION_INFO_V1 ( page_header   ) 
PG_FUNCTION_INFO_V1 ( get_raw_page   ) 
PG_FUNCTION_INFO_V1 ( get_raw_page_fork   ) 

Variable Documentation

Definition at line 27 of file rawpage.c.