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Improve pageinspect module 

Now pageinspect can show data stored in the heap tuple.

Nikolay Shaplov
This commit is contained in:
Teodor Sigaev 2015-11-25 16:31:55 +03:00
parent 13b30c16f3
commit d6061f83a1
5 changed files with 411 additions and 19 deletions
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6
contrib/pageinspect/Makefile
View File

@ -5,9 +5,9 @@ OBJS = rawpage.o heapfuncs.o btreefuncs.o fsmfuncs.o \
brinfuncs.o ginfuncs.o $(WIN32RES)
EXTENSION = pageinspect
DATA = pageinspect--1.3.sql pageinspect--1.2--1.3.sql \
pageinspect--1.1--1.2.sql pageinspect--1.0--1.1.sql \
pageinspect--unpackaged--1.0.sql
DATA = pageinspect--1.4.sql pageinspect--1.3--1.4.sql \
pageinspect--1.2--1.3.sql pageinspect--1.1--1.2.sql \
pageinspect--1.0--1.1.sql pageinspect--unpackaged--1.0.sql
PGFILEDESC = "pageinspect - functions to inspect contents of database pages"
ifdef USE_PGXS

271
contrib/pageinspect/heapfuncs.c
View File

@ -27,8 +27,11 @@
#include "access/htup_details.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/rel.h"
/*
@ -54,6 +57,42 @@ bits_to_text(bits8 *bits, int len)
}
/*
* text_to_bits
*
* Converts a c-string representation of bits into a bits8-array. This is
* the reverse operation of previous routine.
*/
static bits8 *
text_to_bits(char *str, int len)
{
bits8 *bits;
int off = 0;
char byte = 0;
bits = palloc(len + 1);
while (off < len)
{
if (off % 8 == 0)
byte = 0;
if ((str[off] == '0') || (str[off] == '1'))
byte = byte | ((str[off] - '0') << off % 8);
else
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("illegal character '%c' in t_bits string", str[off])));
if (off % 8 == 7)
bits[off / 8] = byte;
off++;
}
return bits;
}
/*
* heap_page_items
*
@ -122,8 +161,8 @@ heap_page_items(PG_FUNCTION_ARGS)
HeapTuple resultTuple;
Datum result;
ItemId id;
Datum values[13];
bool nulls[13];
Datum values[14];
bool nulls[14];
uint16 lp_offset;
uint16 lp_flags;
uint16 lp_len;
@ -153,8 +192,9 @@ heap_page_items(PG_FUNCTION_ARGS)
lp_offset == MAXALIGN(lp_offset) &&
lp_offset + lp_len <= raw_page_size)
{
HeapTupleHeader tuphdr;
int bits_len;
HeapTupleHeader tuphdr;
bytea *tuple_data_bytea;
int tuple_data_len;
/* Extract information from the tuple header */
@ -162,12 +202,21 @@ heap_page_items(PG_FUNCTION_ARGS)
values[4] = UInt32GetDatum(HeapTupleHeaderGetRawXmin(tuphdr));
values[5] = UInt32GetDatum(HeapTupleHeaderGetRawXmax(tuphdr));
values[6] = UInt32GetDatum(HeapTupleHeaderGetRawCommandId(tuphdr)); /* shared with xvac */
/* shared with xvac */
values[6] = UInt32GetDatum(HeapTupleHeaderGetRawCommandId(tuphdr));
values[7] = PointerGetDatum(&tuphdr->t_ctid);
values[8] = UInt32GetDatum(tuphdr->t_infomask2);
values[9] = UInt32GetDatum(tuphdr->t_infomask);
values[10] = UInt8GetDatum(tuphdr->t_hoff);
/* Copy raw tuple data into bytea attribute */
tuple_data_len = lp_len - tuphdr->t_hoff;
tuple_data_bytea = (bytea *) palloc(tuple_data_len + VARHDRSZ);
SET_VARSIZE(tuple_data_bytea, tuple_data_len + VARHDRSZ);
memcpy(VARDATA(tuple_data_bytea), (char *) tuphdr + tuphdr->t_hoff,
tuple_data_len);
values[13] = PointerGetDatum(tuple_data_bytea);
/*
* We already checked that the item is completely within the raw
* page passed to us, with the length given in the line pointer.
@ -180,11 +229,11 @@ heap_page_items(PG_FUNCTION_ARGS)
{
if (tuphdr->t_infomask & HEAP_HASNULL)
{
bits_len = tuphdr->t_hoff -
offsetof(HeapTupleHeaderData, t_bits);
int bits_len =
((tuphdr->t_infomask2 & HEAP_NATTS_MASK) / 8 + 1) * 8;
values[11] = CStringGetTextDatum(
bits_to_text(tuphdr->t_bits, bits_len * 8));
bits_to_text(tuphdr->t_bits, bits_len));
}
else
nulls[11] = true;
@ -208,7 +257,7 @@ heap_page_items(PG_FUNCTION_ARGS)
*/
int i;
for (i = 4; i <= 12; i++)
for (i = 4; i <= 13; i++)
nulls[i] = true;
}
@ -223,3 +272,205 @@ heap_page_items(PG_FUNCTION_ARGS)
else
SRF_RETURN_DONE(fctx);
}
/*
* tuple_data_split_internal
*
* Split raw tuple data taken directly from a page into an array of bytea
* elements. This routine does a lookup on NULL values and creates array
* elements accordindly. This is a reimplementation of nocachegetattr()
* in heaptuple.c simplified for educational purposes.
*/
static Datum
tuple_data_split_internal(Oid relid, char *tupdata,
uint16 tupdata_len, uint16 t_infomask,
uint16 t_infomask2, bits8 *t_bits,
bool do_detoast)
{
ArrayBuildState *raw_attrs;
int nattrs;
int i;
int off = 0;
Relation rel;
TupleDesc tupdesc;
/* Get tuple descriptor from relation OID */
rel = relation_open(relid, NoLock);
tupdesc = CreateTupleDescCopyConstr(rel->rd_att);
relation_close(rel, NoLock);
raw_attrs = initArrayResult(BYTEAOID, CurrentMemoryContext, false);
nattrs = tupdesc->natts;
if (nattrs < (t_infomask2 & HEAP_NATTS_MASK))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("number of attributes in tuple header is greater than number of attributes in tuple descriptor")));
for (i = 0; i < nattrs; i++)
{
Form_pg_attribute attr;
bool is_null;
bytea *attr_data = NULL;
attr = tupdesc->attrs[i];
is_null = (t_infomask & HEAP_HASNULL) && att_isnull(i, t_bits);
/*
* Tuple header can specify less attributes than tuple descriptor
* as ALTER TABLE ADD COLUMN without DEFAULT keyword does not
* actually change tuples in pages, so attributes with numbers greater
* than (t_infomask2 & HEAP_NATTS_MASK) should be treated as NULL.
*/
if (i >= (t_infomask2 & HEAP_NATTS_MASK))
is_null = true;
if (!is_null)
{
int len;
if (attr->attlen == -1)
{
off = att_align_pointer(off, tupdesc->attrs[i]->attalign, -1,
tupdata + off);
/*
* As VARSIZE_ANY throws an exception if it can't properly
* detect the type of external storage in macros VARTAG_SIZE,
* this check is repeated to have a nicer error handling.
*/
if (VARATT_IS_EXTERNAL(tupdata + off) &&
!VARATT_IS_EXTERNAL_ONDISK(tupdata + off) &&
!VARATT_IS_EXTERNAL_INDIRECT(tupdata + off))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("first byte of varlena attribute is incorrect for attribute %d", i)));
len = VARSIZE_ANY(tupdata + off);
}
else
{
off = att_align_nominal(off, tupdesc->attrs[i]->attalign);
len = attr->attlen;
}
if (tupdata_len < off + len)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("unexpected end of tuple data")));
if (attr->attlen == -1 && do_detoast)
attr_data = DatumGetByteaPCopy(tupdata + off);
else
{
attr_data = (bytea *) palloc(len + VARHDRSZ);
SET_VARSIZE(attr_data, len + VARHDRSZ);
memcpy(VARDATA(attr_data), tupdata + off, len);
}
off = att_addlength_pointer(off, tupdesc->attrs[i]->attlen,
tupdata + off);
}
raw_attrs = accumArrayResult(raw_attrs, PointerGetDatum(attr_data),
is_null, BYTEAOID, CurrentMemoryContext);
if (attr_data)
pfree(attr_data);
}
if (tupdata_len != off)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("end of tuple reached without looking at all its data")));
return makeArrayResult(raw_attrs, CurrentMemoryContext);
}
/*
* tuple_data_split
*
* Split raw tuple data taken directly from page into distinct elements
* taking into account null values.
*/
PG_FUNCTION_INFO_V1(tuple_data_split);
Datum
tuple_data_split(PG_FUNCTION_ARGS)
{
Oid relid;
bytea *raw_data;
uint16 t_infomask;
uint16 t_infomask2;
char *t_bits_str;
bool do_detoast = false;
bits8 *t_bits = NULL;
Datum res;
relid = PG_GETARG_OID(0);
raw_data = PG_ARGISNULL(1) ? NULL : PG_GETARG_BYTEA_P(1);
t_infomask = PG_GETARG_INT16(2);
t_infomask2 = PG_GETARG_INT16(3);
t_bits_str = PG_ARGISNULL(4) ? NULL :
text_to_cstring(PG_GETARG_TEXT_PP(4));
if (PG_NARGS() >= 6)
do_detoast = PG_GETARG_BOOL(5);
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use raw page functions")));
if (!raw_data)
PG_RETURN_NULL();
/*
* Convert t_bits string back to the bits8 array as represented in the
* tuple header.
*/
if (t_infomask & HEAP_HASNULL)
{
int bits_str_len;
int bits_len;
bits_len = (t_infomask2 & HEAP_NATTS_MASK) / 8 + 1;
if (!t_bits_str)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("argument of t_bits is null, but it is expected to be null and %i character long",
bits_len * 8)));
bits_str_len = strlen(t_bits_str);
if ((bits_str_len % 8) != 0)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("length of t_bits is not a multiple of eight")));
if (bits_len * 8 != bits_str_len)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("unexpected length of t_bits %u, expected %i",
bits_str_len, bits_len * 8)));
/* do the conversion */
t_bits = text_to_bits(t_bits_str, bits_str_len);
}
else
{
if (t_bits_str)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("t_bits string is expected to be NULL, but instead it is %lu bytes length",
strlen(t_bits_str))));
}
/* Split tuple data */
res = tuple_data_split_internal(relid, (char *) raw_data + VARHDRSZ,
VARSIZE(raw_data) - VARHDRSZ,
t_infomask, t_infomask2, t_bits,
do_detoast);
if (t_bits)
pfree(t_bits);
PG_RETURN_ARRAYTYPE_P(res);
}

94
contrib/pageinspect/pageinspect--1.3.sql → contrib/pageinspect/pageinspect--1.4.sql
View File

@ -1,4 +1,4 @@
/* contrib/pageinspect/pageinspect--1.3.sql */
/* contrib/pageinspect/pageinspect--1.4.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "CREATE EXTENSION pageinspect" to load this file. \quit
@ -48,11 +48,101 @@ CREATE FUNCTION heap_page_items(IN page bytea,
OUT t_infomask integer,
OUT t_hoff smallint,
OUT t_bits text,
OUT t_oid oid)
OUT t_oid oid,
OUT t_data bytea)
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'heap_page_items'
LANGUAGE C STRICT;
--
-- tuple_data_split()
--
CREATE FUNCTION tuple_data_split(rel_oid oid,
t_data bytea,
t_infomask integer,
t_infomask2 integer,
t_bits text)
RETURNS bytea[]
AS 'MODULE_PATHNAME','tuple_data_split'
LANGUAGE C;
CREATE FUNCTION tuple_data_split(rel_oid oid,
t_data bytea,
t_infomask integer,
t_infomask2 integer,
t_bits text,
do_detoast bool)
RETURNS bytea[]
AS 'MODULE_PATHNAME','tuple_data_split'
LANGUAGE C;
--
-- heap_page_item_attrs()
--
CREATE FUNCTION heap_page_item_attrs(
IN page bytea,
IN rel_oid regclass,
IN do_detoast bool,
OUT lp smallint,
OUT lp_off smallint,
OUT lp_flags smallint,
OUT lp_len smallint,
OUT t_xmin xid,
OUT t_xmax xid,
OUT t_field3 int4,
OUT t_ctid tid,
OUT t_infomask2 integer,
OUT t_infomask integer,
OUT t_hoff smallint,
OUT t_bits text,
OUT t_oid oid,
OUT t_attrs bytea[]
)
RETURNS SETOF record AS $$
SELECT lp,
lp_off,
lp_flags,
lp_len,
t_xmin,
t_xmax,
t_field3,
t_ctid,
t_infomask2,
t_infomask,
t_hoff,
t_bits,
t_oid,
tuple_data_split(
rel_oid,
t_data,
t_infomask,
t_infomask2,
t_bits,
do_detoast)
AS t_attrs
FROM heap_page_items(page);
$$ LANGUAGE SQL;
CREATE FUNCTION heap_page_item_attrs(IN page bytea, IN rel_oid regclass,
OUT lp smallint,
OUT lp_off smallint,
OUT lp_flags smallint,
OUT lp_len smallint,
OUT t_xmin xid,
OUT t_xmax xid,
OUT t_field3 int4,
OUT t_ctid tid,
OUT t_infomask2 integer,
OUT t_infomask integer,
OUT t_hoff smallint,
OUT t_bits text,
OUT t_oid oid,
OUT t_attrs bytea[]
)
RETURNS SETOF record AS $$
SELECT * from heap_page_item_attrs(page, rel_oid, false);
$$ LANGUAGE SQL;
--
-- bt_metap()
--

2
contrib/pageinspect/pageinspect.control
View File

@ -1,5 +1,5 @@
# pageinspect extension
comment = 'inspect the contents of database pages at a low level'
default_version = '1.3'
default_version = '1.4'
module_pathname = '$libdir/pageinspect'
relocatable = true

57
doc/src/sgml/pageinspect.sgml
View File

@ -93,9 +93,10 @@ test=# SELECT * FROM page_header(get_raw_page('pg_class', 0));
<listitem>
<para>
<function>heap_page_items</function> shows all line pointers on a heap
page. For those line pointers that are in use, tuple headers are also
shown. All tuples are shown, whether or not the tuples were visible to
an MVCC snapshot at the time the raw page was copied.
page. For those line pointers that are in use, tuple headers as well
as tuple raw data are also shown. All tuples are shown, whether or not
the tuples were visible to an MVCC snapshot at the time the raw page
was copied.
</para>
<para>
A heap page image obtained with <function>get_raw_page</function> should
@ -110,6 +111,56 @@ test=# SELECT * FROM heap_page_items(get_raw_page('pg_class', 0));
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>tuple_data_split(rel_oid, t_data bytea, t_infomask integer, t_infomask2 integer, t_bits text [, do_detoast bool]) returns bytea[]</function>
<indexterm>
<primary>tuple_data_split</primary>
</indexterm>
</term>
<listitem>
<para>
<function>tuple_data_split</function> splits tuple data into attributes
in the same way as backend internals.
<screen>
test=# SELECT tuple_data_split('pg_class'::regclass, t_data, t_infomask, t_infomask2, t_bits) FROM heap_page_items(get_raw_page('pg_class', 0));
</screen>
This function should be called with the same arguments as the return
attributes of <function>heap_page_items</function>.
</para>
<para>
If <parameter>do_detoast</parameter> is <literal>true</literal>,
attribute that will be detoasted as needed. Default value is
<literal>false</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>heap_page_item_attrs(rel_oid, t_data bytea, [, do_detoast bool]) returns bytea[]</function>
<indexterm>
<primary>heap_page_item_attrs</primary>
</indexterm>
</term>
<listitem>
<para>
<function>heap_page_item_attrs</function> is equivalent to
<function>heap_page_items</function> except that it returns
tuple raw data as an array of attributes that can optionally
be detoasted by <parameter>do_detoast</parameter> which is
<literal>false</literal> by default.
</para>
<para>
A heap page image obtained with <function>get_raw_page</function> should
be passed as argument. For example:
<screen>
test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class'::regclass);
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>bt_metap(relname text) returns record</function>