Issues

• Window functions with ORDER BY are up to 1.8 times slower than in 3.0, because the frame is evaluated for every row, also for functions that do not use it (4.0, 5.0, master)

  FirebirdSQL/firebird#9192 · Filter by author tomaszdubiel18 opened on Oct 4, 2026
  3

• Converting TIME WITH TIME ZONE to TIME (e.g. assigning CURRENT_TIME to a TIME variable or column) costs about 4 times more than the equivalent TIMESTAMP conversion with a region session time zone;

  FirebirdSQL/firebird#9191 · Filter by author tomaszdubiel18 opened on Oct 4, 2026

• Hash join uses only the index-matched equality as the hash key; the other join equalities become a post-filter, leading to quadratic probing (5.0, 6.0)

  FirebirdSQL/firebird#9190 · Filter by author tomaszdubiel18 opened on Oct 4, 2026

• Background garbage collector keeps working on a dropped table: bugcheck 259 "bad pointer page" after DROP TABLE + CREATE TABLE, then the server hangs on a page latch left by the GC thread (3.0.14, 4.0.7, 5.0.5)

  FirebirdSQL/firebird#9189 · Filter by author tomaszdubiel18 opened on Oct 4, 2026
  2

• Nested loop join: Bitmap And with an open-ended range scan re-walks the whole range for every outer row (exposed by OuterJoinConversion in 5.0 / 6.0)

  FirebirdSQL/firebird#9188 · Filter by author tomaszdubiel18 opened on Oct 4, 2026

• gbak -c stdin must not request next backup file

  FirebirdSQL/firebird#9187 · Filter by author basid-irk opened on Oct 4, 2026
  3

• LIKE, CONTAINING, STARTING WITH and SIMILAR TO fail on DATE/TIME/TIMESTAMP and approximate numeric operands since #9108

  FirebirdSQL/firebird#9186 · Filter by author madorin opened on Oct 3, 2026

• Regressions in FB 5.x when OuterJoinConversion = true (found by SQLancer with TLP-verification)

  FirebirdSQL/firebird#9183 · Filter by author pavel-zotov opened on Oct 2, 2026
  2

  

• isc_put_slice stores every second VARCHAR array element without character set conversion

  FirebirdSQL/firebird#9180 · Filter by author madorin opened on Oct 2, 2026
  1

• Incorrect filling of MON$COMPILED_STATEMENTS

  FirebirdSQL/firebird#9172 · Filter by author AlexBekhtin opened on Sep 29, 2026
  8

• Windows: no OS read-ahead for the engine's sequential page reads since 4.0 (FILE_FLAG_OVERLAPPED); with a cold cache gfix -v runs 3-9x and gbak 1.4-2.5x slower than on 3.0

  FirebirdSQL/firebird#9170 · Filter by author fdcastel opened on Sep 28, 2026
  2

• SuperServer: no attachment to ANY database can proceed while two or more attachments wait for a database under exclusive validation

  affect-version: 4.0.0affect-version: 5.0 Initialfix-version: 4.0.8fix-version: 5.0.5type: bug
  Bug

  FirebirdSQL/firebird#9169 · Filter by author fdcastel opened on Sep 28, 2026
  5

  

• FB 3.x hangs when user trace session, 'CREATE DATABASE' and 'fbsvcmgr info_svr_db_info' are used at the same time

  FirebirdSQL/firebird#9168 · Filter by author pavel-zotov opened on Sep 25, 2026

• It is impossible to read the value from the SEARCH_PATH context variable if it exceeds 255 characters.

  FirebirdSQL/firebird#9167 · Filter by author AlexBekhtin opened on Sep 25, 2026
  1

• Expression index on a computed column is not usable in other attachments and gets corrupted ("missing entries") when the table has a computed column calling a procedure that reads the same table

  FirebirdSQL/firebird#9165 · Filter by author tomaszdubiel18 opened on Sep 24, 2026
  6

• "Too many concurrent executions of the same request" raises when MaxStatementCacheSize > 0 and connection has lot of prepared statements.

  FirebirdSQL/firebird#9159 · Filter by author pavel-zotov opened on Sep 22, 2026
  1

• Incorrect result HASH SEMI JOIN with UUID key

  affect-version: 5.0.0affect-version: 5.0.1affect-version: 5.0.2affect-version: 5.0.3affect-version: 5.0.4fix-version: 5.0.5type: bug
  Bug

  FirebirdSQL/firebird#9158 · Filter by author sim1984 opened on Sep 19, 2026
  5

  

• ISQL 'set per_table' may produce unreal data in the table statistics if some counter became greater than 2^31

  FirebirdSQL/firebird#9150 · Filter by author pavel-zotov opened on Sep 12, 2026

• Killing a blocked ALTER ... RESTART WITH can leave a primary key index allowing duplicate values

  FirebirdSQL/firebird#9149 · Filter by author LouisCaous opened on Sep 9, 2026
  2

• Names of LOCAL and DECLARED temporary tables that participate in queries can not be easy matched between EXPLAINED PLAN and TRACE table statistics

  type: improvement
  FirebirdSQL/firebird#9147 · Filter by author pavel-zotov opened on Sep 9, 2026
  1

• Add Restart=on-failure in systemd units firebird and firebird-superserver

  affect-version: 3.0.14affect-version: 4.0.7affect-version: 5.0.4affect-version: 6.0 Initialfix-version: 6.0 Alpha 1qa: cannot be tested
  FirebirdSQL/firebird#9141 · Filter by author basid-irk opened on Sep 1, 2026
  5

  

• Event connection listener remains in LISTEN and blocks subsequent event connections

  FirebirdSQL/firebird#9140 · Filter by author jhhenriquee opened on Aug 28, 2026

• Deadlock in Classic Server with self-security database and ON CONNECT trigger that access some MON$ table(s) is possible

  affect-version: 4.0.0affect-version: 5.0.4affect-version: 6.0 Initialfix-version: 4.0.8fix-version: 5.0.5fix-version: 6.0 Alpha 1type: bug
  Bug

  FirebirdSQL/firebird#9136 · Filter by author hvlad opened on Aug 27, 2026
  1

  

• The ability to declare exceptions in a package

  FirebirdSQL/firebird#9133 · Filter by author AlexBekhtin opened on Aug 27, 2026
  1

• An other OuterJoinConversion performance/plan issue

  FirebirdSQL/firebird#9129 · Filter by author EPluribusUnum opened on Aug 19, 2026
  1