Although the new txid functions are very clean 1:1 interface to the internal MVCC info and they don't need much docs in that respect, their "killer" usage comes from the possibility to query txids committed between 2 snapshots.
But how to do that (efficiently) is far from obvious when just looking at the API. So with attached docs patch I try to fill the gap. Here I also show 2 variants for the common query helper function. But I'm pretty bad at SGML, english and writing docs, so please review it. In addition to english/typos/sgml the suspicious aspects are: - code style - writing style - used mostly PgQ terminology (ticks), could there be something better? - giving two variants of helper function may be too much Even the realistic code may be too much for general docs, but considering this is not a functionality covered by general SQL textbooks, I think it is worth having. I also put rendered pages up here: http://skytools.projects.postgresql.org/txid/datatype-txid-snapshot.html http://skytools.projects.postgresql.org/txid/functions-txid.html -- marko
txid-docs.diff.gz
Description: GNU Zip compressed data
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
