Обсуждение: pgsql: Add verification of variable names in pgbench.

Log Message:
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Add verification of variable names in pgbench.

Variables must consist of only alphabets, numerals and underscores.
We had allowed to set variables with invalid names, but could not
refer them in queries.

Thanks to Robert Haas for the review.

Modified Files:
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    pgsql/contrib/pgbench:
        pgbench.c (r1.94 -> r1.95)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pgbench/pgbench.c?r1=1.94&r2=1.95)