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Commitaeb1631

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Mostly-cosmetic adjustments of TOAST-related macros.
The authors ofbbe0a81 hadn't quite got the idea that macros namedlike SOMETHING_4B_C were only meant for internal endianness-relateddetails in postgres.h. Choose more legible names for macros that areintended to be used elsewhere. Rearrange postgres.h a bit to clarifythe separation between those internal macros and ones intended forwider use.Also, avoid using the term "rawsize" for true decompressed size;we've used "extsize" for that, because "rawsize" generally denotestotal Datum size including header. This choice seemed particularlyunfortunate in tests that were comparing one of these meanings tothe other.This patch includes a couple of not-purely-cosmetic changes: besure that the shifts aligning compression methods are unsigned(not critical today, but will be when compression method 2 exists),and fix broken definition of VARATT_EXTERNAL_GET_COMPRESSION (nowVARATT_EXTERNAL_GET_COMPRESS_METHOD), whose callers worked onlyaccidentally.Discussion:https://postgr.es/m/574197.1616428079@sss.pgh.pa.us
1 parent2c75f8a commitaeb1631

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5 files changed

+87
-84
lines changed

5 files changed

+87
-84
lines changed

‎src/backend/access/common/detoast.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -251,7 +251,7 @@ detoast_attr_slice(struct varlena *attr,
251251
* determine how much compressed data we need to be sure of being
252252
* able to decompress the required slice.
253253
*/
254-
if (VARATT_EXTERNAL_GET_COMPRESSION(toast_pointer)==
254+
if (VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer)==
255255
TOAST_PGLZ_COMPRESSION_ID)
256256
max_size=pglz_maximum_compressed_size(slicelimit,max_size);
257257

@@ -562,7 +562,7 @@ toast_raw_datum_size(Datum value)
562562
elseif (VARATT_IS_COMPRESSED(attr))
563563
{
564564
/* here, va_rawsize is just the payload size */
565-
result=VARRAWSIZE_4B_C(attr)+VARHDRSZ;
565+
result=VARDATA_COMPRESSED_GET_EXTSIZE(attr)+VARHDRSZ;
566566
}
567567
elseif (VARATT_IS_SHORT(attr))
568568
{

‎src/backend/access/common/toast_compression.c

Lines changed: 20 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -53,19 +53,19 @@ pglz_compress_datum(const struct varlena *value)
5353
* that will be needed for varlena overhead, and allocate that amount.
5454
*/
5555
tmp= (structvarlena*)palloc(PGLZ_MAX_OUTPUT(valsize)+
56-
VARHDRSZ_COMPRESS);
56+
VARHDRSZ_COMPRESSED);
5757

5858
len=pglz_compress(VARDATA_ANY(value),
5959
valsize,
60-
(char*)tmp+VARHDRSZ_COMPRESS,
60+
(char*)tmp+VARHDRSZ_COMPRESSED,
6161
NULL);
6262
if (len<0)
6363
{
6464
pfree(tmp);
6565
returnNULL;
6666
}
6767

68-
SET_VARSIZE_COMPRESSED(tmp,len+VARHDRSZ_COMPRESS);
68+
SET_VARSIZE_COMPRESSED(tmp,len+VARHDRSZ_COMPRESSED);
6969

7070
returntmp;
7171
}
@@ -80,13 +80,13 @@ pglz_decompress_datum(const struct varlena *value)
8080
int32rawsize;
8181

8282
/* allocate memory for the uncompressed data */
83-
result= (structvarlena*)palloc(VARRAWSIZE_4B_C(value)+VARHDRSZ);
83+
result= (structvarlena*)palloc(VARDATA_COMPRESSED_GET_EXTSIZE(value)+VARHDRSZ);
8484

8585
/* decompress the data */
86-
rawsize=pglz_decompress((char*)value+VARHDRSZ_COMPRESS,
87-
VARSIZE(value)-VARHDRSZ_COMPRESS,
86+
rawsize=pglz_decompress((char*)value+VARHDRSZ_COMPRESSED,
87+
VARSIZE(value)-VARHDRSZ_COMPRESSED,
8888
VARDATA(result),
89-
VARRAWSIZE_4B_C(value), true);
89+
VARDATA_COMPRESSED_GET_EXTSIZE(value), true);
9090
if (rawsize<0)
9191
ereport(ERROR,
9292
(errcode(ERRCODE_DATA_CORRUPTED),
@@ -111,8 +111,8 @@ pglz_decompress_datum_slice(const struct varlena *value,
111111
result= (structvarlena*)palloc(slicelength+VARHDRSZ);
112112

113113
/* decompress the data */
114-
rawsize=pglz_decompress((char*)value+VARHDRSZ_COMPRESS,
115-
VARSIZE(value)-VARHDRSZ_COMPRESS,
114+
rawsize=pglz_decompress((char*)value+VARHDRSZ_COMPRESSED,
115+
VARSIZE(value)-VARHDRSZ_COMPRESSED,
116116
VARDATA(result),
117117
slicelength, false);
118118
if (rawsize<0)
@@ -149,10 +149,10 @@ lz4_compress_datum(const struct varlena *value)
149149
* that will be needed for varlena overhead, and allocate that amount.
150150
*/
151151
max_size=LZ4_compressBound(valsize);
152-
tmp= (structvarlena*)palloc(max_size+VARHDRSZ_COMPRESS);
152+
tmp= (structvarlena*)palloc(max_size+VARHDRSZ_COMPRESSED);
153153

154154
len=LZ4_compress_default(VARDATA_ANY(value),
155-
(char*)tmp+VARHDRSZ_COMPRESS,
155+
(char*)tmp+VARHDRSZ_COMPRESSED,
156156
valsize,max_size);
157157
if (len <=0)
158158
elog(ERROR,"lz4 compression failed");
@@ -164,7 +164,7 @@ lz4_compress_datum(const struct varlena *value)
164164
returnNULL;
165165
}
166166

167-
SET_VARSIZE_COMPRESSED(tmp,len+VARHDRSZ_COMPRESS);
167+
SET_VARSIZE_COMPRESSED(tmp,len+VARHDRSZ_COMPRESSED);
168168

169169
returntmp;
170170
#endif
@@ -184,13 +184,13 @@ lz4_decompress_datum(const struct varlena *value)
184184
structvarlena*result;
185185

186186
/* allocate memory for the uncompressed data */
187-
result= (structvarlena*)palloc(VARRAWSIZE_4B_C(value)+VARHDRSZ);
187+
result= (structvarlena*)palloc(VARDATA_COMPRESSED_GET_EXTSIZE(value)+VARHDRSZ);
188188

189189
/* decompress the data */
190-
rawsize=LZ4_decompress_safe((char*)value+VARHDRSZ_COMPRESS,
190+
rawsize=LZ4_decompress_safe((char*)value+VARHDRSZ_COMPRESSED,
191191
VARDATA(result),
192-
VARSIZE(value)-VARHDRSZ_COMPRESS,
193-
VARRAWSIZE_4B_C(value));
192+
VARSIZE(value)-VARHDRSZ_COMPRESSED,
193+
VARDATA_COMPRESSED_GET_EXTSIZE(value));
194194
if (rawsize<0)
195195
ereport(ERROR,
196196
(errcode(ERRCODE_DATA_CORRUPTED),
@@ -224,9 +224,9 @@ lz4_decompress_datum_slice(const struct varlena *value, int32 slicelength)
224224
result= (structvarlena*)palloc(slicelength+VARHDRSZ);
225225

226226
/* decompress the data */
227-
rawsize=LZ4_decompress_safe_partial((char*)value+VARHDRSZ_COMPRESS,
227+
rawsize=LZ4_decompress_safe_partial((char*)value+VARHDRSZ_COMPRESSED,
228228
VARDATA(result),
229-
VARSIZE(value)-VARHDRSZ_COMPRESS,
229+
VARSIZE(value)-VARHDRSZ_COMPRESSED,
230230
slicelength,
231231
slicelength);
232232
if (rawsize<0)
@@ -262,10 +262,10 @@ toast_get_compression_id(struct varlena *attr)
262262
VARATT_EXTERNAL_GET_POINTER(toast_pointer,attr);
263263

264264
if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
265-
cmid=VARATT_EXTERNAL_GET_COMPRESSION(toast_pointer);
265+
cmid=VARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer);
266266
}
267267
elseif (VARATT_IS_COMPRESSED(attr))
268-
cmid=VARCOMPRESS_4B_C(attr);
268+
cmid=VARDATA_COMPRESSED_GET_COMPRESS_METHOD(attr);
269269

270270
returncmid;
271271
}

‎src/backend/access/common/toast_internals.c

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -91,7 +91,7 @@ toast_compress_datum(Datum value, char cmethod)
9191
{
9292
/* successful compression */
9393
Assert(cmid!=TOAST_INVALID_COMPRESSION_ID);
94-
TOAST_COMPRESS_SET_SIZE_AND_METHOD(tmp,valsize,cmid);
94+
TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(tmp,valsize,cmid);
9595
returnPointerGetDatum(tmp);
9696
}
9797
else
@@ -181,11 +181,11 @@ toast_save_datum(Relation rel, Datum value,
181181
data_p=VARDATA(dval);
182182
data_todo=VARSIZE(dval)-VARHDRSZ;
183183
/* rawsize in a compressed datum is just the size of the payload */
184-
toast_pointer.va_rawsize=VARRAWSIZE_4B_C(dval)+VARHDRSZ;
184+
toast_pointer.va_rawsize=VARDATA_COMPRESSED_GET_EXTSIZE(dval)+VARHDRSZ;
185185

186186
/* set external size and compression method */
187-
VARATT_EXTERNAL_SET_SIZE_AND_COMPRESSION(toast_pointer,data_todo,
188-
VARCOMPRESS_4B_C(dval));
187+
VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer,data_todo,
188+
VARDATA_COMPRESSED_GET_COMPRESS_METHOD(dval));
189189
/* Assert that the numbers look like it's compressed */
190190
Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
191191
}

‎src/include/access/toast_internals.h

Lines changed: 7 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -24,22 +24,23 @@ typedef struct toast_compress_header
2424
{
2525
int32vl_len_;/* varlena header (do not touch directly!) */
2626
uint32tcinfo;/* 2 bits for compression method and 30 bits
27-
*rawsize */
27+
*external size; see va_extinfo */
2828
}toast_compress_header;
2929

3030
/*
3131
* Utilities for manipulation of header information for compressed
3232
* toast entries.
3333
*/
34-
#defineTOAST_COMPRESS_METHOD(ptr)\
35-
(((toast_compress_header *) (ptr))->tcinfo >> VARLENA_RAWSIZE_BITS)
36-
#defineTOAST_COMPRESS_SET_SIZE_AND_METHOD(ptr,len,cm_method) \
34+
#defineTOAST_COMPRESS_METHOD(ptr) \
35+
(((toast_compress_header *) (ptr))->tcinfo >> VARLENA_EXTSIZE_BITS)
36+
37+
#defineTOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(ptr,len,cm_method) \
3738
do { \
38-
Assert((len) > 0 && (len) <=VARLENA_RAWSIZE_MASK); \
39+
Assert((len) > 0 && (len) <=VARLENA_EXTSIZE_MASK); \
3940
Assert((cm_method) == TOAST_PGLZ_COMPRESSION_ID || \
4041
(cm_method) == TOAST_LZ4_COMPRESSION_ID); \
4142
((toast_compress_header *) (ptr))->tcinfo = \
42-
((len) | (cm_method) <<VARLENA_RAWSIZE_BITS); \
43+
(len) | ((uint32) (cm_method) <<VARLENA_EXTSIZE_BITS); \
4344
} while (0)
4445

4546
externDatumtoast_compress_datum(Datumvalue,charcmethod);

‎src/include/postgres.h

Lines changed: 54 additions & 52 deletions
Original file line numberDiff line numberDiff line change
@@ -55,8 +55,8 @@
5555
/*
5656
* struct varatt_external is a traditional "TOAST pointer", that is, the
5757
* information needed to fetch a Datum stored out-of-line in a TOAST table.
58-
* The data is compressed if and only if the size stored in va_extinfo <
59-
* va_rawsize - VARHDRSZ.
58+
* The data is compressed if and only if theexternalsize stored in
59+
*va_extinfo is less thanva_rawsize - VARHDRSZ.
6060
*
6161
* This struct must not contain any padding, because we sometimes compare
6262
* these pointers using memcmp.
@@ -75,6 +75,13 @@ typedef struct varatt_external
7575
Oidva_toastrelid;/* RelID of TOAST table containing it */
7676
}varatt_external;
7777

78+
/*
79+
* These macros define the "saved size" portion of va_extinfo. Its remaining
80+
* two high-order bits identify the compression method.
81+
*/
82+
#defineVARLENA_EXTSIZE_BITS30
83+
#defineVARLENA_EXTSIZE_MASK((1U << VARLENA_EXTSIZE_BITS) - 1)
84+
7885
/*
7986
* struct varatt_indirect is a "TOAST pointer" representing an out-of-line
8087
* Datum that's stored in memory, not in an external toast relation.
@@ -149,7 +156,7 @@ typedef union
149156
{
150157
uint32va_header;
151158
uint32va_tcinfo;/* Original data size (excludes header) and
152-
* compression method */
159+
* compression method; see va_extinfo */
153160
charva_data[FLEXIBLE_ARRAY_MEMBER];/* Compressed data */
154161
}va_compressed;
155162
}varattrib_4b;
@@ -235,6 +242,7 @@ typedef struct
235242
#defineSET_VARTAG_1B_E(PTR,tag) \
236243
(((varattrib_1b_e *) (PTR))->va_header = 0x80, \
237244
((varattrib_1b_e *) (PTR))->va_tag = (tag))
245+
238246
#else/* !WORDS_BIGENDIAN */
239247

240248
#defineVARATT_IS_4B(PTR) \
@@ -267,36 +275,28 @@ typedef struct
267275
#defineSET_VARTAG_1B_E(PTR,tag) \
268276
(((varattrib_1b_e *) (PTR))->va_header = 0x01, \
269277
((varattrib_1b_e *) (PTR))->va_tag = (tag))
270-
#endif/* WORDS_BIGENDIAN */
271278

272-
#defineVARHDRSZ_SHORToffsetof(varattrib_1b, va_data)
273-
#defineVARATT_SHORT_MAX0x7F
274-
#defineVARATT_CAN_MAKE_SHORT(PTR) \
275-
(VARATT_IS_4B_U(PTR) && \
276-
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
277-
#defineVARATT_CONVERTED_SHORT_SIZE(PTR) \
278-
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
279-
280-
#defineVARHDRSZ_EXTERNALoffsetof(varattrib_1b_e, va_data)
281-
#defineVARHDRSZ_COMPRESSoffsetof(varattrib_4b, va_compressed.va_data)
279+
#endif/* WORDS_BIGENDIAN */
282280

283281
#defineVARDATA_4B(PTR)(((varattrib_4b *) (PTR))->va_4byte.va_data)
284282
#defineVARDATA_4B_C(PTR)(((varattrib_4b *) (PTR))->va_compressed.va_data)
285283
#defineVARDATA_1B(PTR)(((varattrib_1b *) (PTR))->va_data)
286284
#defineVARDATA_1B_E(PTR)(((varattrib_1b_e *) (PTR))->va_data)
287285

288-
#defineVARLENA_RAWSIZE_BITS30
289-
#defineVARLENA_RAWSIZE_MASK((1U << VARLENA_RAWSIZE_BITS) - 1)
290-
291286
/*
292-
*va_tcinfo in va_compress contains raw size of datum and compression method.
287+
*Externally visible TOAST macros begin here.
293288
*/
294-
#defineVARRAWSIZE_4B_C(PTR) \
295-
(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo & VARLENA_RAWSIZE_MASK)
296-
#defineVARCOMPRESS_4B_C(PTR) \
297-
(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo >> VARLENA_RAWSIZE_BITS)
298289

299-
/* Externally visible macros */
290+
#defineVARHDRSZ_EXTERNALoffsetof(varattrib_1b_e, va_data)
291+
#defineVARHDRSZ_COMPRESSEDoffsetof(varattrib_4b, va_compressed.va_data)
292+
#defineVARHDRSZ_SHORToffsetof(varattrib_1b, va_data)
293+
294+
#defineVARATT_SHORT_MAX0x7F
295+
#defineVARATT_CAN_MAKE_SHORT(PTR) \
296+
(VARATT_IS_4B_U(PTR) && \
297+
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) <= VARATT_SHORT_MAX)
298+
#defineVARATT_CONVERTED_SHORT_SIZE(PTR) \
299+
(VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT)
300300

301301
/*
302302
* In consumers oblivious to data alignment, call PG_DETOAST_DATUM_PACKED(),
@@ -336,35 +336,6 @@ typedef struct
336336
(VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
337337
#defineVARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \
338338
(VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR)))
339-
340-
/*
341-
* va_extinfo in varatt_external contains actual length of the external data
342-
* and compression method if external data is compressed.
343-
*/
344-
#defineVARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) \
345-
((toast_pointer).va_extinfo & VARLENA_RAWSIZE_MASK)
346-
347-
#defineVARATT_EXTERNAL_SET_SIZE_AND_COMPRESSION(toast_pointer,len,cm) \
348-
do { \
349-
Assert((cm) == TOAST_PGLZ_COMPRESSION_ID || \
350-
(cm) == TOAST_LZ4_COMPRESSION_ID); \
351-
((toast_pointer).va_extinfo = (len) | (cm) << VARLENA_RAWSIZE_BITS); \
352-
} while (0)
353-
354-
#defineVARATT_EXTERNAL_GET_COMPRESSION(PTR) \
355-
((toast_pointer).va_extinfo >> VARLENA_RAWSIZE_BITS)
356-
357-
/*
358-
* Testing whether an externally-stored value is compressed now requires
359-
* comparing size stored in va_extinfo (the actual length of the external data)
360-
* to rawsize (the original uncompressed datum's size). The latter includes
361-
* VARHDRSZ overhead, the former doesn't. We never use compression unless it
362-
* actually saves space, so we expect either equality or less-than.
363-
*/
364-
#defineVARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
365-
(VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) < \
366-
(toast_pointer).va_rawsize - VARHDRSZ)
367-
368339
#defineVARATT_IS_SHORT(PTR)VARATT_IS_1B(PTR)
369340
#defineVARATT_IS_EXTENDED(PTR)(!VARATT_IS_4B_U(PTR))
370341

@@ -390,6 +361,37 @@ typedef struct
390361
#defineVARDATA_ANY(PTR) \
391362
(VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR))
392363

364+
/* Decompressed size and compression method of an external compressed Datum */
365+
#defineVARDATA_COMPRESSED_GET_EXTSIZE(PTR) \
366+
(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo & VARLENA_EXTSIZE_MASK)
367+
#defineVARDATA_COMPRESSED_GET_COMPRESS_METHOD(PTR) \
368+
(((varattrib_4b *) (PTR))->va_compressed.va_tcinfo >> VARLENA_EXTSIZE_BITS)
369+
370+
/* Same, when working directly with a struct varatt_external */
371+
#defineVARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) \
372+
((toast_pointer).va_extinfo & VARLENA_EXTSIZE_MASK)
373+
#defineVARATT_EXTERNAL_GET_COMPRESS_METHOD(toast_pointer) \
374+
((toast_pointer).va_extinfo >> VARLENA_EXTSIZE_BITS)
375+
376+
#defineVARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer,len,cm) \
377+
do { \
378+
Assert((cm) == TOAST_PGLZ_COMPRESSION_ID || \
379+
(cm) == TOAST_LZ4_COMPRESSION_ID); \
380+
((toast_pointer).va_extinfo = \
381+
(len) | ((uint32) (cm) << VARLENA_EXTSIZE_BITS)); \
382+
} while (0)
383+
384+
/*
385+
* Testing whether an externally-stored value is compressed now requires
386+
* comparing size stored in va_extinfo (the actual length of the external data)
387+
* to rawsize (the original uncompressed datum's size). The latter includes
388+
* VARHDRSZ overhead, the former doesn't. We never use compression unless it
389+
* actually saves space, so we expect either equality or less-than.
390+
*/
391+
#defineVARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
392+
(VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) < \
393+
(toast_pointer).va_rawsize - VARHDRSZ)
394+
393395

394396
/* ----------------------------------------------------------------
395397
*Section 2:Datum type + support macros

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