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165 lines
4.2 KiB
C
165 lines
4.2 KiB
C
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/*-------------------------------------------------------------------------
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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, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.1 2007/05/17 19:11:24 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "fmgr.h"
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#include "funcapi.h"
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#include "access/heapam.h"
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#include "access/transam.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_type.h"
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#include "utils/builtins.h"
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#include "miscadmin.h"
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PG_MODULE_MAGIC;
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Datum get_raw_page(PG_FUNCTION_ARGS);
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Datum page_header(PG_FUNCTION_ARGS);
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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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Relation rel;
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RangeVar *relrv;
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bytea *raw_page;
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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 (blkno >= RelationGetNumberOfBlocks(rel))
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elog(ERROR, "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 = ReadBuffer(rel, blkno);
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LockBuffer(buf, BUFFER_LOCK_SHARE);
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memcpy(raw_page_data, BufferGetPage(buf), 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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PG_RETURN_BYTEA_P(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[8];
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bool nulls[8];
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PageHeader page;
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XLogRecPtr lsn;
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char lsnchar[64];
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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 < sizeof(PageHeaderData))
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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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snprintf(lsnchar, sizeof(lsnchar), "%X/%X", lsn.xlogid, lsn.xrecoff);
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values[0] = DirectFunctionCall1(textin, CStringGetDatum(lsnchar));
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values[1] = UInt16GetDatum(PageGetTLI(page));
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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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/* 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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