I'm struggling to find a good way to share code between
bt_page_items(text, int4) and bt_page_items(bytea).
If we do it via the SQL route, as I had suggested, it makes the
extension non-relocatable, and it will also create a bit of a mess
during upgrades.
If doing it in C, it will be a bit tricky to pass the SRF context
around. There is no "DirectFunctionCall within SRF context", AFAICT.
I'm half tempted to just rip out the (text, int4) variants.
In any case, I think we should add bytea variants to all the btree
functions, not just the bt_page_items one.
Attached is the remaining patch after the previous commits.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From 203fa8aeb22d56e2d24ba4a5cf0e48ab5253a212 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Fri, 17 Mar 2017 12:17:29 -0400
Subject: [PATCH v3] pageinspect: Add bt_page_items function with bytea
argument
XXX WIP
Author: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
---
contrib/pageinspect/btreefuncs.c | 126 ++++++++++++++++++++++++++
contrib/pageinspect/expected/btree.out | 13 +++
contrib/pageinspect/pageinspect--1.5--1.6.sql | 14 +++
contrib/pageinspect/sql/btree.sql | 4 +
doc/src/sgml/pageinspect.sgml | 31 +++++++
src/include/access/nbtree.h | 1 +
6 files changed, 189 insertions(+)
diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index 6f35e288fd..36185db19a 100644
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -41,6 +41,7 @@
PG_FUNCTION_INFO_V1(bt_metap);
PG_FUNCTION_INFO_V1(bt_page_items);
+PG_FUNCTION_INFO_V1(bt_page_items_bytea);
PG_FUNCTION_INFO_V1(bt_page_stats);
#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
@@ -396,6 +397,131 @@ bt_page_items(PG_FUNCTION_ARGS)
}
}
+/*-------------------------------------------------------
+ * bt_page_items_bytea()
+ *
+ * Get IndexTupleData set in a btree page
+ *
+ * Usage: SELECT * FROM bt_page_items(get_raw_page('t1_pkey', 1));
+ *-------------------------------------------------------
+ */
+
+Datum
+bt_page_items_bytea(PG_FUNCTION_ARGS)
+{
+ bytea *raw_page = PG_GETARG_BYTEA_P(0);
+ Datum result;
+ char *values[6];
+ HeapTuple tuple;
+ FuncCallContext *fctx;
+ struct user_args *uargs;
+ int raw_page_size;
+
+ if (!superuser())
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ (errmsg("must be superuser to use pageinspect functions"))));
+
+ if (SRF_IS_FIRSTCALL())
+ {
+ BTPageOpaque opaque;
+ MemoryContext mctx;
+ TupleDesc tupleDesc;
+
+ raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
+
+ if (raw_page_size < SizeOfPageHeaderData)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("input page too small (%d bytes)", raw_page_size)));
+
+ fctx = SRF_FIRSTCALL_INIT();
+ mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
+
+ uargs = palloc(sizeof(struct user_args));
+
+ uargs->page = VARDATA(raw_page);
+
+ uargs->offset = FirstOffsetNumber;
+
+ opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
+
+ if (P_ISMETA(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("block is a meta page")));
+
+ if (P_ISDELETED(opaque))
+ elog(NOTICE, "page is deleted");
+
+ fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
+
+ /* Build a tuple descriptor for our result type */
+ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
+ elog(ERROR, "return type must be a row type");
+
+ fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc);
+
+ fctx->user_fctx = uargs;
+
+ MemoryContextSwitchTo(mctx);
+ }
+
+ fctx = SRF_PERCALL_SETUP();
+ uargs = fctx->user_fctx;
+
+ if (fctx->call_cntr < fctx->max_calls)
+ {
+ ItemId id;
+ IndexTuple itup;
+ int j;
+ int off;
+ int dlen;
+ char *dump;
+ char *ptr;
+
+ id = PageGetItemId(uargs->page, uargs->offset);
+
+ if (!ItemIdIsValid(id))
+ elog(ERROR, "invalid ItemId");
+
+ itup = (IndexTuple) PageGetItem(uargs->page, id);
+
+ j = 0;
+ values[j++] = psprintf("%d", uargs->offset);
+ values[j++] = psprintf("(%u,%u)",
+ BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid)),
+ itup->t_tid.ip_posid);
+ values[j++] = psprintf("%d", (int) IndexTupleSize(itup));
+ values[j++] = psprintf("%c", IndexTupleHasNulls(itup) ? 't' : 'f');
+ values[j++] = psprintf("%c", IndexTupleHasVarwidths(itup) ? 't' : 'f');
+
+ ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
+ dlen = IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
+ dump = palloc0(dlen * 3 + 1);
+ values[j] = dump;
+ for (off = 0; off < dlen; off++)
+ {
+ if (off > 0)
+ *dump++ = ' ';
+ sprintf(dump, "%02x", *(ptr + off) & 0xff);
+ dump += 2;
+ }
+
+ tuple = BuildTupleFromCStrings(fctx->attinmeta, values);
+ result = HeapTupleGetDatum(tuple);
+
+ uargs->offset = uargs->offset + 1;
+
+ SRF_RETURN_NEXT(fctx, result);
+ }
+ else
+ {
+ pfree(uargs);
+ SRF_RETURN_DONE(fctx);
+ }
+}
+
/* ------------------------------------------------
* bt_metap()
diff --git a/contrib/pageinspect/expected/btree.out b/contrib/pageinspect/expected/btree.out
index 82a49e3d6c..67b103add3 100644
--- a/contrib/pageinspect/expected/btree.out
+++ b/contrib/pageinspect/expected/btree.out
@@ -42,4 +42,17 @@ data | 01 00 00 00 00 00 00 01
SELECT * FROM bt_page_items('test1_a_idx', 2);
ERROR: block number out of range
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 0));
+ERROR: block is a meta page
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 1));
+-[ RECORD 1 ]-----------------------
+itemoffset | 1
+ctid | (0,1)
+itemlen | 16
+nulls | f
+vars | f
+data | 01 00 00 00 00 00 00 01
+
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 2));
+ERROR: block number 2 is out of range for relation "test1_a_idx"
DROP TABLE test1;
diff --git a/contrib/pageinspect/pageinspect--1.5--1.6.sql b/contrib/pageinspect/pageinspect--1.5--1.6.sql
index 6ac2a8011d..c4356288db 100644
--- a/contrib/pageinspect/pageinspect--1.5--1.6.sql
+++ b/contrib/pageinspect/pageinspect--1.5--1.6.sql
@@ -83,3 +83,17 @@ CREATE FUNCTION page_checksum(IN page bytea, IN blkno int4)
RETURNS smallint
AS 'MODULE_PATHNAME', 'page_checksum'
LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- bt_page_items_bytea()
+--
+CREATE FUNCTION bt_page_items(IN page bytea,
+ OUT itemoffset smallint,
+ OUT ctid tid,
+ OUT itemlen smallint,
+ OUT nulls bool,
+ OUT vars bool,
+ OUT data text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'bt_page_items_bytea'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/sql/btree.sql b/contrib/pageinspect/sql/btree.sql
index 1eafc3249c..8eac64c7b3 100644
--- a/contrib/pageinspect/sql/btree.sql
+++ b/contrib/pageinspect/sql/btree.sql
@@ -14,4 +14,8 @@ CREATE INDEX test1_a_idx ON test1 USING btree (a);
SELECT * FROM bt_page_items('test1_a_idx', 1);
SELECT * FROM bt_page_items('test1_a_idx', 2);
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 0));
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 1));
+SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 2));
+
DROP TABLE test1;
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 9f41bb21eb..1e225724a7 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -333,6 +333,37 @@ <title>B-tree Functions</title>
</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term>
+ <function>bt_page_items(page bytea) returns setof record</function>
+ <indexterm>
+ <primary>bt_page_items</primary>
+ </indexterm>
+ </term>
+
+ <listitem>
+ <para>
+ Similarly to <function>heap_page_items</function>, it is also possible to
+ pass the page to <function>bt_page_items</function> as a <type>bytea</>
+ value. So the last example may also be rewritten like this:
+<screen>
+test=# SELECT * FROM bt_page_items(get_raw_page('pg_cast_oid_index', 1));
+ itemoffset | ctid | itemlen | nulls | vars | data
+------------+---------+---------+-------+------+-------------
+ 1 | (0,1) | 12 | f | f | 23 27 00 00
+ 2 | (0,2) | 12 | f | f | 24 27 00 00
+ 3 | (0,3) | 12 | f | f | 25 27 00 00
+ 4 | (0,4) | 12 | f | f | 26 27 00 00
+ 5 | (0,5) | 12 | f | f | 27 27 00 00
+ 6 | (0,6) | 12 | f | f | 28 27 00 00
+ 7 | (0,7) | 12 | f | f | 29 27 00 00
+ 8 | (0,8) | 12 | f | f | 2a 27 00 00
+</screen>
+ All the other details are the same as explained in the previous section.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
</sect2>
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 6289ffa9bd..f202715482 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -177,6 +177,7 @@ typedef struct BTMetaPageData
#define P_ISLEAF(opaque) ((opaque)->btpo_flags & BTP_LEAF)
#define P_ISROOT(opaque) ((opaque)->btpo_flags & BTP_ROOT)
#define P_ISDELETED(opaque) ((opaque)->btpo_flags & BTP_DELETED)
+#define P_ISMETA(opaque) ((opaque)->btpo_flags & BTP_META)
#define P_ISHALFDEAD(opaque) ((opaque)->btpo_flags & BTP_HALF_DEAD)
#define P_IGNORE(opaque) ((opaque)->btpo_flags & (BTP_DELETED|BTP_HALF_DEAD))
#define P_HAS_GARBAGE(opaque) ((opaque)->btpo_flags & BTP_HAS_GARBAGE)
--
2.12.0
--
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