Fix overly-strict assertions in spgtextproc.c.

spg_text_inner_consistent is capable of reconstructing an empty string
to pass down to the next index level; this happens if we have an empty
string coming in, no prefix, and a dummy node label.  (In practice, what
is needed to trigger that is insertion of a whole bunch of empty-string
values.)  Then, we will arrive at the next level with in->level == 0
and a non-NULL (but zero length) in->reconstructedValue, which is valid
but the Assert tests weren't expecting it.

Per report from Andreas Seltenreich.  This has no impact in non-Assert
builds, so should not be a problem in production, but back-patch to
all affected branches anyway.

In passing, remove a couple of useless variable initializations and
shorten the code by not duplicating DatumGetPointer() calls.

diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 5e0629f7d0d4c8062826bb6583a1f4140a71bfdf..e0d8f30ef16c1e44f2861875ec948f6143a7559f 100644 (file)
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -403,8 +403,9 @@ spg_text_inner_consistent(PG_FUNCTION_ARGS)
    spgInnerConsistentIn *in = (spgInnerConsistentIn *) PG_GETARG_POINTER(0);
    spgInnerConsistentOut *out = (spgInnerConsistentOut *) PG_GETARG_POINTER(1);
    bool        collate_is_c = lc_collate_is_c(PG_GET_COLLATION());
-   text       *reconstrText = NULL;
-   int         maxReconstrLen = 0;
+   text       *reconstructedValue;
+   text       *reconstrText;
+   int         maxReconstrLen;
    text       *prefixText = NULL;
    int         prefixSize = 0;
    int         i;
@@ -420,8 +421,9 @@ spg_text_inner_consistent(PG_FUNCTION_ARGS)
     * created by a previous invocation of this routine, and we always emit
     * long-format reconstructed values.
     */
-   Assert(in->level == 0 ? DatumGetPointer(in->reconstructedValue) == NULL :
-   VARSIZE_ANY_EXHDR(DatumGetPointer(in->reconstructedValue)) == in->level);
+   reconstructedValue = (text *) DatumGetPointer(in->reconstructedValue);
+   Assert(reconstructedValue == NULL ? in->level == 0 :
+          VARSIZE_ANY_EXHDR(reconstructedValue) == in->level);
 
    maxReconstrLen = in->level + 1;
    if (in->hasPrefix)
@@ -436,7 +438,7 @@ spg_text_inner_consistent(PG_FUNCTION_ARGS)
 
    if (in->level)
        memcpy(VARDATA(reconstrText),
-              VARDATA(DatumGetPointer(in->reconstructedValue)),
+              VARDATA(reconstructedValue),
               in->level);
    if (prefixSize)
        memcpy(((char *) VARDATA(reconstrText)) + in->level,
@@ -560,7 +562,7 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
    if (DatumGetPointer(in->reconstructedValue))
        reconstrValue = DatumGetTextP(in->reconstructedValue);
 
-   Assert(level == 0 ? reconstrValue == NULL :
+   Assert(reconstrValue == NULL ? level == 0 :
           VARSIZE_ANY_EXHDR(reconstrValue) == level);
 
    /* Reconstruct the full string represented by this leaf tuple */