Horton

Re: support for MERGE

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Amit Langote <amitlangote09@gmail.com>, Japin Li <japinli@hotmail.com>, Zhihong Yu <zyu@yugabyte.com>, Simon Riggs <simon.riggs@enterprisedb.com>, pgsql-hackers@lists.postgresql.org, Tomas Vondra <tomas.vondra@enterprisedb.com>, Daniel Westermann <dwe@dbi-services.com>, Erik Rijkers <er@xs4all.nl>, Jaime Casanova <jcasanov@systemguards.com.ec>, Andres Freund <andres@anarazel.de>
Date: 2022-05-18T16:58:03Z
Lists: pgsql-hackers 
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> I chose the other way :-)

I don't think the committed patch will behave nicely in edge cases:

+           if (es->format == EXPLAIN_FORMAT_TEXT && total > 0)
+           {
+               ExplainIndentText(es);
+               appendStringInfoString(es->str, "Tuples:");
+               if (insert_path > 0)
+                   appendStringInfo(es->str, " inserted=%.0f", insert_path);
+               if (update_path > 0)
+                   appendStringInfo(es->str, " updated=%.0f", update_path);
+               if (delete_path > 0)
+                   appendStringInfo(es->str, " deleted=%.0f", delete_path);
+               if (skipped_path > 0)
+                   appendStringInfo(es->str, " skipped=%.0f", skipped_path);
+               appendStringInfoChar(es->str, '\n');
+           }
+           else
+           {
+               ExplainPropertyFloat("Tuples Inserted", NULL, insert_path, 0, es);
+               ExplainPropertyFloat("Tuples Updated", NULL, update_path, 0, es);
+               ExplainPropertyFloat("Tuples Deleted", NULL, delete_path, 0, es);
+               ExplainPropertyFloat("Tuples Skipped", NULL, skipped_path, 0, es);
+           }

If it's text format and total is 0, I'd wish it to print nothing,
not to revert to the verbose format.

			regards, tom lane

Commits

  1. Doc fixes for MERGE statement

  2. MERGE docs adjustments

  3. Link to MVCC docs in MERGE docs

  4. Fix EXPLAIN MERGE output when no tuples are processed

  5. Make EXPLAIN MERGE output format more compact

  6. Add support for MERGE SQL command

  7. Split ExecUpdate and ExecDelete into reusable pieces

  8. Add API of sorts for transition table handling in trigger.c

  9. Represent Lists as expansible arrays, not chains of cons-cells.