Fix recent pg_walinspect fpi_length bug.

Commit 0276ae42dd taught pg_walinspect's pg_get_wal_record_info()
function to output NULLs rather than empty strings for its record
description and block_ref output parameters.  However, it inadvertently
moved the function call that sets fpi_length until after it was already
set.  As a result, pg_get_wal_record_info() always output spurious
fpi_length values of 0.

Fix by switching the order back (but keep the behavioral change).

Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/CAH2-WzkJmgSYkt6-smQ+57SxSmov+EKqFZdSimFewosoL_JKoA@mail.gmail.com

diff --git a/contrib/pg_walinspect/pg_walinspect.c b/contrib/pg_walinspect/pg_walinspect.c
index 2933734122b78330f740cad7669efaf4945bb486..062e90dbce9b931ec6165e3da112ab71cdbc7958 100644 (file)
--- a/contrib/pg_walinspect/pg_walinspect.c
+++ b/contrib/pg_walinspect/pg_walinspect.c
@@ -186,6 +186,7 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
        RmgrData        desc;
        uint32          fpi_len = 0;
        StringInfoData rec_desc;
+       StringInfoData rec_blk_ref;
        int                     i = 0;
 
        desc = GetRmgr(XLogRecGetRmid(record));
@@ -197,6 +198,12 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
        initStringInfo(&rec_desc);
        desc.rm_desc(&rec_desc, record);
 
+       if (XLogRecHasAnyBlockRefs(record))
+       {
+               initStringInfo(&rec_blk_ref);
+               XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
+       }
+
        values[i++] = LSNGetDatum(record->ReadRecPtr);
        values[i++] = LSNGetDatum(record->EndRecPtr);
        values[i++] = LSNGetDatum(XLogRecGetPrev(record));
@@ -205,7 +212,6 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
        values[i++] = CStringGetTextDatum(id);
        values[i++] = UInt32GetDatum(XLogRecGetTotalLen(record));
        values[i++] = UInt32GetDatum(XLogRecGetDataLen(record));
-
        values[i++] = UInt32GetDatum(fpi_len);
 
        if (rec_desc.len > 0)
@@ -213,15 +219,8 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
        else
                nulls[i++] = true;
 
-       /* Block references. */
        if (XLogRecHasAnyBlockRefs(record))
-       {
-               StringInfoData rec_blk_ref;
-
-               initStringInfo(&rec_blk_ref);
-               XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
                values[i++] = CStringGetTextDatum(rec_blk_ref.data);
-       }
        else
                nulls[i++] = true;