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Improve pageinspect module

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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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271
contrib/pageinspect/heapfuncs.c
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@ -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);
}