pgsql: nbtree: Remove useless 'strat' local variable.

nbtree: Remove useless 'strat' local variable.

Remove a local variable that was used to avoid overwriting strat_total
with the = operator strategy when a >= operator strategy key was already
included in the initial positioning/insertion scan keys by _bt_first
(for backwards scans it would have to be a <= key that was included).
_bt_first's strat_total local variable now simply tracks the operator
strategy of the final scan key that was included in the scan's insertion
scan key (barring the case where the !used_all_subkeys row compare path
adjusts strat_total in its own way).

_bt_first already treated >= keys (or <= keys) as = keys for initial
positioning purposes. There is no good reason to remember that that was
what happened; no later _bt_first step cares about the distinction.
Note, in particular, that the insertion scan key's 'nextkey' and
'backward' fields will be initialized the same way regardless.

Author: Peter Geoghegan <pg(at)bowt(dot)ie>
Reviewed-By: Tomas Vondra <tomas(at)vondra(dot)me>
Discussion: https://postgr.es/m/CAH2-Wz=PKR6rB7qbx+Vnd7eqeB5VTcrW=iJvAsTsKbdG+kW_UA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b6558e4f837e5c8f923e405ef6ab957ac2bd095a

Modified Files
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src/backend/access/nbtree/nbtsearch.c | 18 +++++-------------
1 file changed, 5 insertions(+), 13 deletions(-)