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Getting from get_raw_page() an all-zero page is considered as a valid case by the buffer manager and it can happen for example when finding a corrupted page with zero_damaged_pages enabled (using zero_damaged_pages to look at corrupted pages happens), or after a crash when a relation file is extended before any WAL for its new data is generated (before a vacuum or autovacuum job comes in to do some cleanup). However, all the functions of pageinspect, as of the index AMs (except hash that has its own idea of new pages), heap, the FSM or the page header have never worked with all-zero pages, causing various crashes when going through the page internals. This commit changes all the pageinspect functions to be compliant with all-zero pages, where the choice is made to return NULL or no rows for SRFs when finding a new page. get_raw_page() still works the same way, returning a batch of zeros in the bytea of the page retrieved. A hard error could be used but NULL, while more invasive, is useful when scanning relation files in full to get a batch of results for a single relation in one query. Tests are added for all the code paths impacted. Reported-by: Daria Lepikhova Author: Michael Paquier Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru Backpatch-through: 10
441 lines
11 KiB
C
441 lines
11 KiB
C
/*
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* brinfuncs.c
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* Functions to investigate BRIN indexes
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*
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* Copyright (c) 2014-2020, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/pageinspect/brinfuncs.c
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*/
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#include "postgres.h"
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#include "access/brin.h"
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#include "access/brin_internal.h"
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#include "access/brin_page.h"
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#include "access/brin_revmap.h"
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#include "access/brin_tuple.h"
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#include "access/htup_details.h"
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#include "catalog/index.h"
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#include "catalog/pg_am_d.h"
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#include "catalog/pg_type.h"
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#include "funcapi.h"
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#include "lib/stringinfo.h"
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#include "miscadmin.h"
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#include "pageinspect.h"
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#include "utils/array.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/rel.h"
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PG_FUNCTION_INFO_V1(brin_page_type);
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PG_FUNCTION_INFO_V1(brin_page_items);
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PG_FUNCTION_INFO_V1(brin_metapage_info);
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PG_FUNCTION_INFO_V1(brin_revmap_data);
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#define IS_BRIN(r) ((r)->rd_rel->relam == BRIN_AM_OID)
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typedef struct brin_column_state
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{
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int nstored;
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FmgrInfo outputFn[FLEXIBLE_ARRAY_MEMBER];
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} brin_column_state;
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static Page verify_brin_page(bytea *raw_page, uint16 type,
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const char *strtype);
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Datum
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brin_page_type(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page;
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char *type;
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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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page = get_page_from_raw(raw_page);
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if (PageIsNew(page))
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PG_RETURN_NULL();
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/* verify the special space has the expected size */
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if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page is not a valid %s page", "BRIN"),
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errdetail("Expected special size %d, got %d.",
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(int) MAXALIGN(sizeof(BrinSpecialSpace)),
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(int) PageGetSpecialSize(page))));
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switch (BrinPageType(page))
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{
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case BRIN_PAGETYPE_META:
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type = "meta";
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break;
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case BRIN_PAGETYPE_REVMAP:
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type = "revmap";
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break;
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case BRIN_PAGETYPE_REGULAR:
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type = "regular";
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break;
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default:
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type = psprintf("unknown (%02x)", BrinPageType(page));
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break;
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}
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PG_RETURN_TEXT_P(cstring_to_text(type));
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}
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/*
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* Verify that the given bytea contains a BRIN page of the indicated page
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* type, or die in the attempt. A pointer to the page is returned.
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*/
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static Page
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verify_brin_page(bytea *raw_page, uint16 type, const char *strtype)
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{
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Page page = get_page_from_raw(raw_page);
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if (PageIsNew(page))
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return page;
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/* verify the special space has the expected size */
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if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BrinSpecialSpace)))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page is not a valid %s page", "BRIN"),
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errdetail("Expected special size %d, got %d.",
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(int) MAXALIGN(sizeof(BrinSpecialSpace)),
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(int) PageGetSpecialSize(page))));
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/* verify the special space says this page is what we want */
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if (BrinPageType(page) != type)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("page is not a BRIN page of type \"%s\"", strtype),
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errdetail("Expected special type %08x, got %08x.",
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type, BrinPageType(page))));
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return page;
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}
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/*
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* Extract all item values from a BRIN index page
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*
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* Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass);
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*/
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Datum
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brin_page_items(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Oid indexRelid = PG_GETARG_OID(1);
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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TupleDesc tupdesc;
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MemoryContext oldcontext;
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Tuplestorestate *tupstore;
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Relation indexRel;
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brin_column_state **columns;
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BrinDesc *bdesc;
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BrinMemTuple *dtup;
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Page page;
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OffsetNumber offset;
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AttrNumber attno;
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bool unusedItem;
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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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/* check to see if caller supports us returning a tuplestore */
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if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("set-valued function called in context that cannot accept a set")));
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if (!(rsinfo->allowedModes & SFRM_Materialize) ||
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rsinfo->expectedDesc == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("materialize mode required, but it is not allowed in this context")));
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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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/* Build tuplestore to hold the result rows */
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oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
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tupstore = tuplestore_begin_heap(true, false, work_mem);
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rsinfo->returnMode = SFRM_Materialize;
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rsinfo->setResult = tupstore;
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rsinfo->setDesc = tupdesc;
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MemoryContextSwitchTo(oldcontext);
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indexRel = index_open(indexRelid, AccessShareLock);
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if (!IS_BRIN(indexRel))
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a %s index",
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RelationGetRelationName(indexRel), "BRIN")));
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bdesc = brin_build_desc(indexRel);
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
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if (PageIsNew(page))
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{
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brin_free_desc(bdesc);
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index_close(indexRel, AccessShareLock);
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PG_RETURN_NULL();
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}
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/*
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* Initialize output functions for all indexed datatypes; simplifies
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* calling them later.
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*/
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columns = palloc(sizeof(brin_column_state *) * RelationGetDescr(indexRel)->natts);
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for (attno = 1; attno <= bdesc->bd_tupdesc->natts; attno++)
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{
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Oid output;
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bool isVarlena;
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BrinOpcInfo *opcinfo;
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int i;
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brin_column_state *column;
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opcinfo = bdesc->bd_info[attno - 1];
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column = palloc(offsetof(brin_column_state, outputFn) +
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sizeof(FmgrInfo) * opcinfo->oi_nstored);
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column->nstored = opcinfo->oi_nstored;
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for (i = 0; i < opcinfo->oi_nstored; i++)
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{
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getTypeOutputInfo(opcinfo->oi_typcache[i]->type_id, &output, &isVarlena);
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fmgr_info(output, &column->outputFn[i]);
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}
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columns[attno - 1] = column;
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}
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offset = FirstOffsetNumber;
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unusedItem = false;
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dtup = NULL;
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for (;;)
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{
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Datum values[7];
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bool nulls[7];
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/*
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* This loop is called once for every attribute of every tuple in the
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* page. At the start of a tuple, we get a NULL dtup; that's our
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* signal for obtaining and decoding the next one. If that's not the
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* case, we output the next attribute.
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*/
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if (dtup == NULL)
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{
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ItemId itemId;
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/* verify item status: if there's no data, we can't decode */
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itemId = PageGetItemId(page, offset);
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if (ItemIdIsUsed(itemId))
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{
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dtup = brin_deform_tuple(bdesc,
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(BrinTuple *) PageGetItem(page, itemId),
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NULL);
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attno = 1;
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unusedItem = false;
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}
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else
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unusedItem = true;
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}
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else
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attno++;
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MemSet(nulls, 0, sizeof(nulls));
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if (unusedItem)
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{
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values[0] = UInt16GetDatum(offset);
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nulls[1] = true;
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nulls[2] = true;
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nulls[3] = true;
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nulls[4] = true;
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nulls[5] = true;
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nulls[6] = true;
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}
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else
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{
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int att = attno - 1;
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values[0] = UInt16GetDatum(offset);
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values[1] = UInt32GetDatum(dtup->bt_blkno);
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values[2] = UInt16GetDatum(attno);
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values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
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values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
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values[5] = BoolGetDatum(dtup->bt_placeholder);
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if (!dtup->bt_columns[att].bv_allnulls)
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{
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BrinValues *bvalues = &dtup->bt_columns[att];
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StringInfoData s;
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bool first;
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int i;
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initStringInfo(&s);
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appendStringInfoChar(&s, '{');
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first = true;
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for (i = 0; i < columns[att]->nstored; i++)
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{
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char *val;
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if (!first)
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appendStringInfoString(&s, " .. ");
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first = false;
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val = OutputFunctionCall(&columns[att]->outputFn[i],
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bvalues->bv_values[i]);
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appendStringInfoString(&s, val);
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pfree(val);
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}
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appendStringInfoChar(&s, '}');
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values[6] = CStringGetTextDatum(s.data);
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pfree(s.data);
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}
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else
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{
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nulls[6] = true;
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}
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}
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tuplestore_putvalues(tupstore, tupdesc, values, nulls);
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/*
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* If the item was unused, jump straight to the next one; otherwise,
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* the only cleanup needed here is to set our signal to go to the next
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* tuple in the following iteration, by freeing the current one.
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*/
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if (unusedItem)
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offset = OffsetNumberNext(offset);
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else if (attno >= bdesc->bd_tupdesc->natts)
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{
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pfree(dtup);
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dtup = NULL;
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offset = OffsetNumberNext(offset);
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}
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/*
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* If we're beyond the end of the page, we're done.
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*/
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if (offset > PageGetMaxOffsetNumber(page))
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break;
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}
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/* clean up and return the tuplestore */
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brin_free_desc(bdesc);
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tuplestore_donestoring(tupstore);
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index_close(indexRel, AccessShareLock);
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return (Datum) 0;
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}
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Datum
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brin_metapage_info(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page;
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BrinMetaPageData *meta;
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TupleDesc tupdesc;
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Datum values[4];
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bool nulls[4];
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HeapTuple htup;
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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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page = verify_brin_page(raw_page, BRIN_PAGETYPE_META, "metapage");
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if (PageIsNew(page))
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PG_RETURN_NULL();
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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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tupdesc = BlessTupleDesc(tupdesc);
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/* Extract values from the metapage */
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meta = (BrinMetaPageData *) PageGetContents(page);
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = CStringGetTextDatum(psprintf("0x%08X", meta->brinMagic));
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values[1] = Int32GetDatum(meta->brinVersion);
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values[2] = Int32GetDatum(meta->pagesPerRange);
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values[3] = Int64GetDatum(meta->lastRevmapPage);
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htup = heap_form_tuple(tupdesc, values, nulls);
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PG_RETURN_DATUM(HeapTupleGetDatum(htup));
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}
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/*
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* Return the TID array stored in a BRIN revmap page
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*/
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Datum
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brin_revmap_data(PG_FUNCTION_ARGS)
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{
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struct
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{
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ItemPointerData *tids;
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int idx;
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} *state;
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FuncCallContext *fctx;
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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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if (SRF_IS_FIRSTCALL())
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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MemoryContext mctx;
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Page page;
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/* create a function context for cross-call persistence */
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fctx = SRF_FIRSTCALL_INIT();
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/* switch to memory context appropriate for multiple function calls */
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mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REVMAP, "revmap");
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if (PageIsNew(page))
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{
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MemoryContextSwitchTo(mctx);
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PG_RETURN_NULL();
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}
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state = palloc(sizeof(*state));
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state->tids = ((RevmapContents *) PageGetContents(page))->rm_tids;
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state->idx = 0;
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fctx->user_fctx = state;
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MemoryContextSwitchTo(mctx);
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}
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fctx = SRF_PERCALL_SETUP();
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state = fctx->user_fctx;
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if (state->idx < REVMAP_PAGE_MAXITEMS)
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SRF_RETURN_NEXT(fctx, PointerGetDatum(&state->tids[state->idx++]));
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SRF_RETURN_DONE(fctx);
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}
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