Oracle’s heuristics previously avoided considering fixed tables for Join Predicate Pushdown (JPPD) transformation, leading to suboptimal plans. Enforcing predicate pushing into the view with the PUSH_PRED hint was a workaround. Oracle addressed this in the 21c release, evaluating fixed tables for JPPD. Continue Reading
New optimization causing severe performance degradation. It can be switched off with the fix control. Continue Reading
Database writer performance impaired by sudden debug trace. Continue Reading
Reasons for not using NVL for filtering NULL values. Join cardinality estimate improvement in Oracle 21c. Continue Reading
Oracle internals for understanding cryptic error messages during materialized view refresh Continue Reading
ORA-00904: invalid identifier when creating materialized view in 19.13 and 19.14. The problem is fixed in 21c. Continue Reading
Column usage in predicates can trigger statistics collection even when statistics aren’t stale. The problem got worse in 21c. Continue Reading
We run multiple database Apex instances configurations on a single Tomcat. After migrating from Apex 18c to 21c we couldn’t access Apex anymore. The error was misleading: https://server/ords21/DBNAME 404 Not Found 2021-10-29T17:12:42.556Z | HyrcATg4C7e87ph3eRaCig | ORDS-22001 The procedure named DBNAME… Continue Reading
Reports containing SQL expressions with redacted columns will break in versions 18c higher. Worth checking before Apex upgrade. Continue Reading
Inline hint can cause ORA-07445 in 18c and 19c. Continue Reading