amcheck: Support for different header sizes of short varlena datum

In the heap, tuples may contain short varlena datum with both 1B header and 4B
headers.  But the corresponding index tuple should always have such varlena's
with 1B headers.  So, for fingerprinting, we need to convert.

Backpatch to all supported versions.

Discussion: https://postgr.es/m/flat/7bdbe559-d61a-4ae4-a6e1-48abdf3024cc%40postgrespro.ru
Author: Michael Zhilin
Reviewed-by: Alexander Lakhin, Andrey Borodin, Jian He, Alexander Korotkov
Backpatch-through: 12

diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index 0fd6ea09f1c5d9fda2201c3704a992af7df1c460..fecbeb05beb7a793ec69e2887e5630fec5097755 100644 (file)
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -190,6 +190,18 @@ SELECT bt_index_check('bttest_a_expr_idx', true);
  
 (1 row)
 
+-- Check support of both 1B and 4B header sizes of short varlena datum
+CREATE TABLE varlena_bug (v text);
+ALTER TABLE varlena_bug ALTER column v SET storage plain;
+INSERT INTO varlena_bug VALUES ('x');
+COPY varlena_bug from stdin;
+CREATE INDEX varlena_bug_idx on varlena_bug(v);
+SELECT bt_index_check('varlena_bug_idx', true);
+ bt_index_check 
+----------------
+ 
+(1 row)
+
 -- cleanup
 DROP TABLE bttest_a;
 DROP TABLE bttest_b;
@@ -199,3 +211,4 @@ DROP TABLE toast_bug;
 DROP FUNCTION ifun(int8);
 DROP OWNED BY regress_bttest_role; -- permissions
 DROP ROLE regress_bttest_role;
+DROP TABLE varlena_bug;

diff --git a/contrib/amcheck/sql/check_btree.sql b/contrib/amcheck/sql/check_btree.sql
index 324818774d22c35c5e3f8f5b6d2764bb360b9648..b65df1219304d542bc29694909c78e7215243f25 100644 (file)
--- a/contrib/amcheck/sql/check_btree.sql
+++ b/contrib/amcheck/sql/check_btree.sql
@@ -130,6 +130,16 @@ CREATE INDEX bttest_a_expr_idx ON bttest_a ((ifun(id) + ifun(0)))
 
 SELECT bt_index_check('bttest_a_expr_idx', true);
 
+-- Check support of both 1B and 4B header sizes of short varlena datum
+CREATE TABLE varlena_bug (v text);
+ALTER TABLE varlena_bug ALTER column v SET storage plain;
+INSERT INTO varlena_bug VALUES ('x');
+COPY varlena_bug from stdin;
+x
+\.
+CREATE INDEX varlena_bug_idx on varlena_bug(v);
+SELECT bt_index_check('varlena_bug_idx', true);
+
 -- cleanup
 DROP TABLE bttest_a;
 DROP TABLE bttest_b;
@@ -139,3 +149,4 @@ DROP TABLE toast_bug;
 DROP FUNCTION ifun(int8);
 DROP OWNED BY regress_bttest_role; -- permissions
 DROP ROLE regress_bttest_role;
+DROP TABLE varlena_bug;

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index dcdcb9b0745b0200dfe01fe803e0b42a87bbc8d4..fa94c6c9b4140114374aef07671e1830565d0a79 100644 (file)
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -2058,7 +2058,7 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
    TupleDesc   tupleDescriptor = RelationGetDescr(state->rel);
    Datum       normalized[INDEX_MAX_KEYS];
    bool        isnull[INDEX_MAX_KEYS];
-   bool        toast_free[INDEX_MAX_KEYS];
+   bool        need_free[INDEX_MAX_KEYS];
    bool        formnewtup = false;
    IndexTuple  reformed;
    int         i;
@@ -2074,7 +2074,7 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
        att = TupleDescAttr(tupleDescriptor, i);
 
        /* Assume untoasted/already normalized datum initially */
-       toast_free[i] = false;
+       need_free[i] = false;
        normalized[i] = index_getattr(itup, att->attnum,
                                      tupleDescriptor,
                                      &isnull[i]);
@@ -2097,11 +2097,32 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
        {
            formnewtup = true;
            normalized[i] = PointerGetDatum(PG_DETOAST_DATUM(normalized[i]));
-           toast_free[i] = true;
+           need_free[i] = true;
+       }
+
+       /*
+        * Short tuples may have 1B or 4B header. Convert 4B header of short
+        * tuples to 1B
+        */
+       else if (VARATT_CAN_MAKE_SHORT(DatumGetPointer(normalized[i])))
+       {
+           /* convert to short varlena */
+           Size        len = VARATT_CONVERTED_SHORT_SIZE(DatumGetPointer(normalized[i]));
+           char       *data = palloc(len);
+
+           SET_VARSIZE_SHORT(data, len);
+           memcpy(data + 1, VARDATA(DatumGetPointer(normalized[i])), len - 1);
+
+           formnewtup = true;
+           normalized[i] = PointerGetDatum(data);
+           need_free[i] = true;
        }
    }
 
-   /* Easier case: Tuple has varlena datums, none of which are compressed */
+   /*
+    * Easier case: Tuple has varlena datums, none of which are compressed or
+    * short with 4B header
+    */
    if (!formnewtup)
        return itup;
 
@@ -2111,6 +2132,11 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
     * (normalized input datums).  This is rather naive, but shouldn't be
     * necessary too often.
     *
+    * In the heap, tuples may contain short varlena datums with both 1B
+    * header and 4B headers.  But the corresponding index tuple should always
+    * have such varlena's with 1B headers.  So, if there is a short varlena
+    * with 4B header, we need to convert it for for fingerprinting.
+    *
     * Note that we rely on deterministic index_form_tuple() TOAST compression
     * of normalized input.
     */
@@ -2119,7 +2145,7 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
 
    /* Cannot leak memory here */
    for (i = 0; i < tupleDescriptor->natts; i++)
-       if (toast_free[i])
+       if (need_free[i])
            pfree(DatumGetPointer(normalized[i]));
 
    return reformed;