Add functions to 'pageinspect' to inspect GiST indexes.

Author: Andrey Borodin and me
Discussion: https://www.postgresql.org/message-id/3E4F9093-A1B5-4DF8-A292-0B48692E3954%40yandex-team.ru

1 files changed, 287 insertions, 0 deletions

diff --git a/contrib/pageinspect/gistfuncs.c b/contrib/pageinspect/gistfuncs.c
new file mode 100644
index 00000000000..146b2e91b60
--- /dev/null
+++ b/contrib/pageinspect/gistfuncs.c
@@ -0,0 +1,287 @@
+/*
+ * gistfuncs.c
+ *		Functions to investigate the content of GiST indexes
+ *
+ * Copyright (c) 2014-2020, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		contrib/pageinspect/gistfuncs.c
+ */
+#include "postgres.h"
+
+#include "access/gist.h"
+#include "access/gist_private.h"
+#include "access/htup.h"
+#include "access/relation.h"
+#include "catalog/namespace.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "pageinspect.h"
+#include "storage/itemptr.h"
+#include "utils/array.h"
+#include "utils/builtins.h"
+#include "utils/rel.h"
+#include "utils/pg_lsn.h"
+#include "utils/varlena.h"
+
+PG_FUNCTION_INFO_V1(gist_page_opaque_info);
+PG_FUNCTION_INFO_V1(gist_page_items);
+PG_FUNCTION_INFO_V1(gist_page_items_bytea);
+
+#define ItemPointerGetDatum(X)	 PointerGetDatum(X)
+
+
+Datum
+gist_page_opaque_info(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	TupleDesc	tupdesc;
+	Page		page;
+	GISTPageOpaque opaq;
+	HeapTuple	resultTuple;
+	Datum		values[4];
+	bool		nulls[4];
+	Datum		flags[16];
+	int			nflags = 0;
+	uint16		flagbits;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	page = get_page_from_raw(raw_page);
+
+	opaq = (GISTPageOpaque) PageGetSpecialPointer(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");
+
+	/* Convert the flags bitmask to an array of human-readable names */
+	flagbits = opaq->flags;
+	if (flagbits & F_LEAF)
+		flags[nflags++] = CStringGetTextDatum("leaf");
+	if (flagbits & F_DELETED)
+		flags[nflags++] = CStringGetTextDatum("deleted");
+	if (flagbits & F_TUPLES_DELETED)
+		flags[nflags++] = CStringGetTextDatum("tuples_deleted");
+	if (flagbits & F_FOLLOW_RIGHT)
+		flags[nflags++] = CStringGetTextDatum("follow_right");
+	if (flagbits & F_HAS_GARBAGE)
+		flags[nflags++] = CStringGetTextDatum("has_garbage");
+	flagbits &= ~(F_LEAF | F_DELETED | F_TUPLES_DELETED | F_FOLLOW_RIGHT | F_HAS_GARBAGE);
+	if (flagbits)
+	{
+		/* any flags we don't recognize are printed in hex */
+		flags[nflags++] = DirectFunctionCall1(to_hex32, Int32GetDatum(flagbits));
+	}
+
+	memset(nulls, 0, sizeof(nulls));
+
+	values[0] = LSNGetDatum(PageGetLSN(page));
+	values[1] = LSNGetDatum(GistPageGetNSN(page));
+	values[2] = Int64GetDatum(opaq->rightlink);
+	values[3] = PointerGetDatum(construct_array(flags, nflags,
+												TEXTOID,
+												-1, false, TYPALIGN_INT));
+
+	/* Build and return the result tuple. */
+	resultTuple = heap_form_tuple(tupdesc, values, nulls);
+
+	return HeapTupleGetDatum(resultTuple);
+}
+
+typedef struct gist_page_items_state
+{
+	Page		page;
+	TupleDesc	tupd;
+	OffsetNumber offset;
+	Relation	rel;
+} gist_page_items_state;
+
+Datum
+gist_page_items_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	FuncCallContext *fctx;
+	gist_page_items_state *inter_call_data;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		TupleDesc	tupdesc;
+		MemoryContext mctx;
+		Page		page;
+
+		fctx = SRF_FIRSTCALL_INIT();
+		mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
+
+		page = get_page_from_raw(raw_page);
+
+		inter_call_data = palloc(sizeof(gist_page_items_state));
+
+		/* 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");
+
+		if (GistPageIsDeleted(page))
+			elog(NOTICE, "page is deleted");
+
+		inter_call_data->page = page;
+		inter_call_data->tupd = tupdesc;
+		inter_call_data->offset = FirstOffsetNumber;
+
+		fctx->max_calls = PageGetMaxOffsetNumber(page);
+		fctx->user_fctx = inter_call_data;
+
+		MemoryContextSwitchTo(mctx);
+	}
+
+	fctx = SRF_PERCALL_SETUP();
+	inter_call_data = fctx->user_fctx;
+
+	if (fctx->call_cntr < fctx->max_calls)
+	{
+		Page		page = inter_call_data->page;
+		OffsetNumber offset = inter_call_data->offset;
+		HeapTuple	resultTuple;
+		Datum		result;
+		Datum		values[4];
+		bool		nulls[4];
+		ItemId		id;
+		IndexTuple	itup;
+		bytea	   *tuple_bytea;
+		int			tuple_len;
+
+		id = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(id))
+			elog(ERROR, "invalid ItemId");
+
+		itup = (IndexTuple) PageGetItem(page, id);
+		tuple_len = IndexTupleSize(itup);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = DatumGetInt16(offset);
+		values[1] = ItemPointerGetDatum(&itup->t_tid);
+		values[2] = Int32GetDatum((int) IndexTupleSize(itup));
+
+		tuple_bytea = (bytea *) palloc(tuple_len + VARHDRSZ);
+		SET_VARSIZE(tuple_bytea, tuple_len + VARHDRSZ);
+		memcpy(VARDATA(tuple_bytea), itup, tuple_len);
+		values[3] = PointerGetDatum(tuple_bytea);
+
+		/* Build and return the result tuple. */
+		resultTuple = heap_form_tuple(inter_call_data->tupd, values, nulls);
+		result = HeapTupleGetDatum(resultTuple);
+
+		inter_call_data->offset++;
+		SRF_RETURN_NEXT(fctx, result);
+	}
+
+	SRF_RETURN_DONE(fctx);
+}
+
+Datum
+gist_page_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	FuncCallContext *fctx;
+	gist_page_items_state *inter_call_data;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		Relation	indexRel;
+		TupleDesc	tupdesc;
+		MemoryContext mctx;
+		Page		page;
+
+		fctx = SRF_FIRSTCALL_INIT();
+		mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
+
+		page = get_page_from_raw(raw_page);
+
+		inter_call_data = palloc(sizeof(gist_page_items_state));
+
+		/* Open the relation */
+		indexRel = index_open(indexRelid, AccessShareLock);
+
+		/* 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");
+
+		if (GistPageIsDeleted(page))
+			elog(NOTICE, "page is deleted");
+
+		inter_call_data->page = page;
+		inter_call_data->tupd = tupdesc;
+		inter_call_data->offset = FirstOffsetNumber;
+		inter_call_data->rel = indexRel;
+
+		fctx->max_calls = PageGetMaxOffsetNumber(page);
+		fctx->user_fctx = inter_call_data;
+
+		MemoryContextSwitchTo(mctx);
+	}
+
+	fctx = SRF_PERCALL_SETUP();
+	inter_call_data = fctx->user_fctx;
+
+	if (fctx->call_cntr < fctx->max_calls)
+	{
+		Page		page = inter_call_data->page;
+		OffsetNumber offset = inter_call_data->offset;
+		HeapTuple	resultTuple;
+		Datum		result;
+		Datum		values[4];
+		bool		nulls[4];
+		ItemId		id;
+		IndexTuple	itup;
+		Datum		itup_values[INDEX_MAX_KEYS];
+		bool		itup_isnull[INDEX_MAX_KEYS];
+		char	   *key_desc;
+
+		id = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(id))
+			elog(ERROR, "invalid ItemId");
+
+		itup = (IndexTuple) PageGetItem(page, id);
+
+		index_deform_tuple(itup, RelationGetDescr(inter_call_data->rel),
+						   itup_values, itup_isnull);
+
+		key_desc = BuildIndexValueDescription(inter_call_data->rel, itup_values,
+											  itup_isnull);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = DatumGetInt16(offset);
+		values[1] = ItemPointerGetDatum(&itup->t_tid);
+		values[2] = Int32GetDatum((int) IndexTupleSize(itup));
+		values[3] = CStringGetTextDatum(key_desc);
+
+		/* Build and return the result tuple. */
+		resultTuple = heap_form_tuple(inter_call_data->tupd, values, nulls);
+		result = HeapTupleGetDatum(resultTuple);
+
+		inter_call_data->offset++;
+		SRF_RETURN_NEXT(fctx, result);
+	}
+
+	relation_close(inter_call_data->rel, AccessShareLock);
+
+	SRF_RETURN_DONE(fctx);
+}