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8b65cf4c5e
This patch is a no-op patch which is intended to reduce the chances of failures of omission once the functional part of the "snapshot too old" patch goes in. It adds parameters for snapshot, relation, and an enum to specify whether the snapshot age check needs to be done for the page at this point. This initial patch passes NULL for the first two new parameters and BGP_NO_SNAPSHOT_TEST for the third. The follow-on patch will change the places where the test needs to be made.
241 lines
6.2 KiB
C
241 lines
6.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* rawpage.c
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* Functions to extract a raw page as bytea and inspect it
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*
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* Access-method specific inspection functions are in separate files.
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*
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* Copyright (c) 2007-2016, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/pageinspect/rawpage.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "catalog/catalog.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_type.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
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#include "utils/builtins.h"
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#include "utils/pg_lsn.h"
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#include "utils/rel.h"
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PG_MODULE_MAGIC;
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static bytea *get_raw_page_internal(text *relname, ForkNumber forknum,
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BlockNumber blkno);
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/*
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* get_raw_page
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*
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* Returns a copy of a page from shared buffers as a bytea
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*/
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PG_FUNCTION_INFO_V1(get_raw_page);
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Datum
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get_raw_page(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_P(0);
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uint32 blkno = PG_GETARG_UINT32(1);
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bytea *raw_page;
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/*
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* We don't normally bother to check the number of arguments to a C
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* function, but here it's needed for safety because early 8.4 beta
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* releases mistakenly redefined get_raw_page() as taking three arguments.
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*/
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if (PG_NARGS() != 2)
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ereport(ERROR,
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(errmsg("wrong number of arguments to get_raw_page()"),
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errhint("Run the updated pageinspect.sql script.")));
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raw_page = get_raw_page_internal(relname, MAIN_FORKNUM, blkno);
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PG_RETURN_BYTEA_P(raw_page);
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}
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/*
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* get_raw_page_fork
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*
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* Same, for any fork
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*/
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PG_FUNCTION_INFO_V1(get_raw_page_fork);
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Datum
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get_raw_page_fork(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_P(0);
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text *forkname = PG_GETARG_TEXT_P(1);
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uint32 blkno = PG_GETARG_UINT32(2);
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bytea *raw_page;
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ForkNumber forknum;
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forknum = forkname_to_number(text_to_cstring(forkname));
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raw_page = get_raw_page_internal(relname, forknum, blkno);
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PG_RETURN_BYTEA_P(raw_page);
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}
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/*
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* workhorse
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*/
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static bytea *
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get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno)
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{
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bytea *raw_page;
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RangeVar *relrv;
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Relation rel;
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char *raw_page_data;
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Buffer buf;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw functions"))));
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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rel = relation_openrv(relrv, AccessShareLock);
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/* Check that this relation has storage */
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if (rel->rd_rel->relkind == RELKIND_VIEW)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("cannot get raw page from view \"%s\"",
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RelationGetRelationName(rel))));
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if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("cannot get raw page from composite type \"%s\"",
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RelationGetRelationName(rel))));
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if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("cannot get raw page from foreign table \"%s\"",
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RelationGetRelationName(rel))));
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/*
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* Reject attempts to read non-local temporary relations; we would be
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* likely to get wrong data since we have no visibility into the owning
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* session's local buffers.
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*/
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if (RELATION_IS_OTHER_TEMP(rel))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot access temporary tables of other sessions")));
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if (blkno >= RelationGetNumberOfBlocksInFork(rel, forknum))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("block number %u is out of range for relation \"%s\"",
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blkno, RelationGetRelationName(rel))));
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/* Initialize buffer to copy to */
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raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ);
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SET_VARSIZE(raw_page, BLCKSZ + VARHDRSZ);
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raw_page_data = VARDATA(raw_page);
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/* Take a verbatim copy of the page */
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buf = ReadBufferExtended(rel, forknum, blkno, RBM_NORMAL, NULL);
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LockBuffer(buf, BUFFER_LOCK_SHARE);
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memcpy(raw_page_data,
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BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST),
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BLCKSZ);
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LockBuffer(buf, BUFFER_LOCK_UNLOCK);
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ReleaseBuffer(buf);
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relation_close(rel, AccessShareLock);
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return raw_page;
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}
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/*
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* page_header
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*
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* Allows inspection of page header fields of a raw page
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*/
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PG_FUNCTION_INFO_V1(page_header);
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Datum
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page_header(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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int raw_page_size;
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TupleDesc tupdesc;
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Datum result;
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HeapTuple tuple;
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Datum values[9];
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bool nulls[9];
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PageHeader page;
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XLogRecPtr lsn;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
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/*
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* Check that enough data was supplied, so that we don't try to access
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* fields outside the supplied buffer.
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*/
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if (raw_page_size < SizeOfPageHeaderData)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page too small (%d bytes)", raw_page_size)));
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page = (PageHeader) VARDATA(raw_page);
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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/* Extract information from the page header */
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lsn = PageGetLSN(page);
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/* pageinspect >= 1.2 uses pg_lsn instead of text for the LSN field. */
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if (tupdesc->attrs[0]->atttypid == TEXTOID)
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{
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char lsnchar[64];
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snprintf(lsnchar, sizeof(lsnchar), "%X/%X",
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(uint32) (lsn >> 32), (uint32) lsn);
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values[0] = CStringGetTextDatum(lsnchar);
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}
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else
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values[0] = LSNGetDatum(lsn);
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values[1] = UInt16GetDatum(page->pd_checksum);
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values[2] = UInt16GetDatum(page->pd_flags);
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values[3] = UInt16GetDatum(page->pd_lower);
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values[4] = UInt16GetDatum(page->pd_upper);
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values[5] = UInt16GetDatum(page->pd_special);
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values[6] = UInt16GetDatum(PageGetPageSize(page));
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values[7] = UInt16GetDatum(PageGetPageLayoutVersion(page));
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values[8] = TransactionIdGetDatum(page->pd_prune_xid);
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/* Build and return the tuple. */
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memset(nulls, 0, sizeof(nulls));
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tuple = heap_form_tuple(tupdesc, values, nulls);
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result = HeapTupleGetDatum(tuple);
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PG_RETURN_DATUM(result);
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}
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