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twelve1995 opened this issue Aug 13, 2018 · 1 comment
Open

Questions about the dedicated-database parameter #10

twelve1995 opened this issue Aug 13, 2018 · 1 comment

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@twelve1995
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HI，
I have been confused about me for a few days.
In fact, for a dedicated database connection, you also need to add the backend process to the pool. But I don't understand how you can make the connection to the dedicated database not limited by the size of the pool.
Maybe this is not a good question. But hope you can help me solve
Thank you.
@knizhnik
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Hi
Sorry, I do not completely understand the question. In case of dedicated connection, postmaster is spawning normal backend process which is terminated on client disconnect. So there is no difference in handling dedicated connections with standard Postgres. Pool size doesn't somehow affect dedicated connections.

knizhnik pushed a commit that referenced this issue Mar 25, 2019
@petere
Collations with nondeterministic comparison
5e1963f 
This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

This functionality is only supported with the ICU provider.  At least
glibc doesn't appear to have any locales that work in a
nondeterministic way, so it's not worth supporting this for the libc
provider.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Reviewed-by: Daniel Verite <[email protected]>
Reviewed-by: Peter Geoghegan <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/[email protected]
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@knizhnik @twelve1995