pgsql: Speed up array element assignment in plpgsql by caching type inf

Speed up array element assignment in plpgsql by caching type information.

Cache assorted data in the PLpgSQL_arrayelem struct to avoid repetitive
catalog lookups over multiple executions of the same statement.

Pavel Stehule

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/16762b519c9421ad5f1e373b1d89b0f2f6568769

Modified Files
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src/pl/plpgsql/src/gram.y | 2 +
src/pl/plpgsql/src/pl_exec.c | 102 ++++++++++++++++++++------------
src/pl/plpgsql/src/plpgsql.h | 10 +++
src/test/regress/expected/plpgsql.out | 62 ++++++++++++++++++++
src/test/regress/sql/plpgsql.sql | 41 +++++++++++++
5 files changed, 179 insertions(+), 38 deletions(-)