How to Find Slow SQL Statements with V$SQL and V$SQLSTATS
Rank SQL statements by total and per-execution time with V$SQLSTATS, read child cursors in V$SQL, and show the top statement's plan.
How to Read Join Methods in Oracle Execution Plans: Nested Loops, Hash Join, and Merge Join
See nested loops, hash joins and sort-merge joins in real Oracle plans, learn when each is chosen, and compare their cost on one query.
How to Read Table and Index Access Paths in Oracle Execution Plans
See every common Oracle access path in a real plan, learn when the optimizer picks it, and why a full scan is sometimes faster than an index.
How to Read an Execution Plan in Oracle
Get a plan with EXPLAIN PLAN and DBMS_XPLAN, read its operations in the right order, and compare the estimates with actual rows.
How to Deploy APEX Applications with SQLcl Projects
Release an APEX application and its schema changes together with SQLcl Projects and Git, deploy them to production, and check what arrived.
How to Export and Import APEX Applications with SQLcl
Export an APEX application with SQLcl, split it into files for Git, review a change, and install it in another workspace under a new ID.
How to Fix ORA-01652: Unable to Extend Temp Segment in Oracle
Reproduce a full temporary tablespace, let its file grow to a limit, and find the statements that use the most temp space.
How to Fix ORA-01045: User Lacks CREATE SESSION Privilege; Logon Denied in Oracle
Grant CREATE SESSION, or a role that includes it, so a new user can connect, with the error and fix run on a real database.
How to Fix ORA-01950: No Privileges on Tablespace in Oracle
See why CREATE TABLE works but INSERT fails without a quota, and grant the user a sized quota on the tablespace.
How to Fix ORA-65096: Common User or Role Name Must Start with Prefix C## in Oracle
Check which container the session is in, create application users in the pluggable database, and use C## only for common users.
How to Fix ORA-28001: The Password Has Expired in Oracle
Change an expired password at logon or as an administrator, and check the profile limits that make passwords expire.
How to Fix ORA-28000: The Account Is Locked in Oracle
Reproduce an account lock from failed logins, read LOCKED and LOCKED(TIMED) in DBA_USERS, and unlock the account.
How to Fix ORA-01017: Invalid Username/Password; Logon Denied in Oracle
Find why a logon is denied, from case-sensitive passwords to the wrong pluggable database, and reset the password as an administrator.
How to Fix ORA-12514: Listener Does Not Currently Know of Service Requested in Oracle
List the services the listener knows, connect to the pluggable database's service, and get a database registered again.
How to Fix ORA-12541: TNS No Listener in Oracle
Find where the listener really listens with lsnrctl status, start it when it is down, and check ports, Docker, and firewalls.
How to Fix ORA-12154: TNS Could Not Resolve the Connect Identifier in Oracle
Connect with an Easy Connect string, or add the alias to the tnsnames.ora the client really reads, with tested examples.
How to Handle ORA-01476: Divisor Is Equal to Zero in PL/SQL Loops
Keep a PL/SQL batch running when one row divides by zero, by handling ZERO_DIVIDE per row or using NULLIF in SQL.
How to Fix ORA-04098: Trigger Is Invalid and Failed Re-Validation in Oracle
Find why a trigger is invalid in USER_ERRORS, fix it so statements on the table work again, or disable it until it is fixed.