On 8/11/16 8:45 AM, Tom Lane wrote:
Jim Nasby <Jim.Nasby@xxxxxxxxxxxxxx> writes:
I never dug into why. As Tom posited, decompression might explain the
time to get a single key out. Getting 10 keys instead of just 1 wasn't
10x more expensive, but it was significantly more expensive than just
getting a single key.
What were you doing to "get ten keys out"? If those were ten separate
JSON operators, they'd likely have done ten separate decompressions.
You'd have saved something by having the TOAST data already fetched into
shared buffers, but it'd still hardly be free.
Multiple -> or ->> operators, but all operating on the same field (which
I thought would mean a single datum that would end up detoasted?).
Some of these would have been nested ->/->>. In essence, this was a set
of nested views that ultimately pulled from a single JSONB field.
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Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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