pgsql: pgbench: Allow changing weights for scripts

pgbench: Allow changing weights for scripts

Previously, all scripts had the same probability of being chosen when
multiple of them were specified via -b, -f, -N, -S.  With this commit,
-b and -f now search for an "@" in the script name and use the integer
found after it as the drawing probability for that script.

(One disadvantage is that if you have script whose names contain @, you
are now forced to specify "@1" at the end; otherwise the name's @ is
confused with a weight separator.  We don't expect many pgbench script
with @ in their names in the wild, so this shouldn't be too serious a
problem.)

While at it, rework the interface between addScript, process_file,
process_builtin, and findBuiltin.  It had gotten a bit out of hand with
recent commits.

Author: Fabien Coelho
Reviewed-By: Andres Freund, Robert Haas, Álvaro Herrera, Michaël Paquier
Discussion: http://www.postgresql.org/message-id/alpine.DEB.2.10.1603160721240.1666@sto

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7bafffea647e21864cb857ab5b6fe266f2d0976a

Modified Files
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doc/src/sgml/ref/pgbench.sgml |  25 +++--
src/bin/pgbench/pgbench.c     | 232 ++++++++++++++++++++++++++++--------------
2 files changed, 170 insertions(+), 87 deletions(-)