Hi.
in firebird 2.5

Simple descriptables

table_ud
ud_id integernotnullprimarykey
field_udvarchar(6)

rowcount: 383322

table_tmp
ud_id  integer 
cnd    integer 

index (cnd)

rowcount: 617

UPDATEtable_udud
SETud.field_ud = '201401'
WHEREud.ud_id in (SELECT t.ud_id FROMtable_tmp t where t.cnd = 2)

stadistic 
table_ud
read no index: 383322

Why?

Thistable can growtomillionsofrows

How do I optimizeit ?

Thank
Germán from Buenos Aires

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