Recently someone asked on Slack about what is transaction wraparound. Full answer is a bit too much for slack reply, but I can try to explain it in here.
Tag: slack
Stop the war in Ukraine
Since yesterday my sites (explain.depesz.com, paste.depesz.com, and this blog) are no longer available from IPs that are in Russia or Belarus.
I know this is not huge loss for them, but, I think, every single bit counts.
If you'd like to do the same thing for their site/service:
How to index data with tsearch?
Someone asked recently on Slack, whether one should build tsvector data in a field, and index it, or make index on expression.
We talked about it for a while, and I thought I'll reformat my thoughts into blogpost to avoid retyping it next time.
Does varchar(n) use less disk space than varchar() or text?
Some time ago on Slack some person said:
varchar is better (storage efficiency), i recommend using it for less than 2048 chars, for the best : TEXT
There was discussion that followed, the person that claimed this efficiency never backed their claim, saying only that:
VARChar takes much less ‘place' than TEXT … but have to face it to believe it
and when I asked for
Show me db fiddle with queries that show this difference and I'll believe
I got:
HA ha ! i let you dig it  i've some work ….
I reacted (over reacted), and the thread died.
I know (knew?) that varchar/text are the same internally (wrote about it), but perhaps there have been recent change?
Continue reading Does varchar(n) use less disk space than varchar() or text?
Why is it hard to automatically suggest what index to create?
Every now and then someone asks me to add index suggestions to explain.depesz.com.
I always respond with polite decline. This is complicated thing to do, and I just don't have that time.
Lately I was asked, on Slack to add (to explain.depesz.com) link to pganalyze Index Advisor for Postgres.
So I checked it out. And results prompted me to write this blogpost.
Continue reading Why is it hard to automatically suggest what index to create?