Submitted by: @pavel-zotov

Attachments:
inlist_1500_elements.zip

The following batch will generate script with list of 1500 literals for testing of performance of:

SELECT 1 FROM RDB$DATABASE WHERE :n IN ( <this_huge_list> ):

@echo off
setlocal enabledelayedexpansion enableextensions
set sql=inlist.sql
del %sql% 2>nul
set n=1500
echo show version;>>%sql%
echo set stat on;>>%sql%
echo select 1 from>>%sql%
echo rdb$database where %n% in(>>%sql%
set /a k=2147483647
set str=(
for /l %%i in (1, 1, %n%) do (
echo !k!
if .%%i.==.1. (
echo !k!>>%sql%
) else (
if .%%i.==.%n%. (
echo ,%n%>>%sql%
) else (
echo ,!k!>>%sql%
)
)
set /a k=!k!-1
)
echo );>>%sql%

(script can be taken also from attached .zip)

Results in 3.0 and old 2.5.0:

ISQL Version: WI-T3.0.0.31756 Firebird 3.0 Beta 2
Server version:
Firebird/Windows/Intel/i386 (access method), version "WI-T3.0.0.31756 Firebird 3.0 Beta 2"
Firebird/Windows/Intel/i386 (remote server), version "WI-T3.0.0.31756 Firebird 3.0 Beta 2/tcp (csprog)/P13"
Firebird/Windows/Intel/i386 (remote interface), version "WI-T3.0.0.31756 Firebird 3.0 Beta 2/tcp (csprog)/P13"
on disk structure version 12.0

CONSTANT

============
1

Current memory = 94624048
Delta memory = 57537952
Max memory = 94692960
Elapsed time= 0.794 sec
Buffers = 8192
Reads = 1
Writes = 0
Fetches = 12

=== vs ===

ISQL Version: WI-V2.5.0.26074 Firebird 2.5
Server version:
Firebird/x86/Windows NT (access method), version "WI-V2.5.0.26074 Firebird 2.5"
Firebird/x86/Windows NT (remote server), version "WI-V2.5.0.26074 Firebird 2.5/tcp (csprog)/P12"
Firebird/x86/Windows NT (remote interface), version "WI-V2.5.0.26074 Firebird 2.5/tcp (csprog)/P12"
on disk structure version 11.2

CONSTANT

============
1

Current memory = 36255732
Delta memory = 727292
Max memory = 36314920
Elapsed time= 0.02 sec
Buffers = 8192
Reads = 17
Writes 0
Fetches = 263

Why the elapsed time in 3.0 is more than 100x worse than in 2.5.x ?