Skip to content
DBA Corner

Practical database knowledge

Keep your databases running.

Oracle, SQL Server, backup, and recovery. Practical guides for diagnosing problems and getting your data back.

Featured series · 3 parts

Oracle SQL tuning with AWR & ASH

Follow the investigation from the first slowdown to a stable execution plan.

01 · AWR

Find and prove the regression

Identify the SQL, compare execution plans, and establish what changed.

Start with Part 1 →

02 · ASH

Find where the time went

Use ASH and runtime plans to understand waits and execution work.

Read Part 2 →

03 · Plan stability

Tune and stabilize the plan

Evaluate advisor recommendations and stabilize a proven execution plan.

Read Part 3 →

Latest articles

  • Sep 16, 2026
    Guide

    Oracle SQL Tuning with AWR and ASH, Part 3: SQL Tuning Advisor, sqltrpt.sql, and Plan Stabilization

    Use the evidence from AWR and ASH to evaluate tuning recommendations and stabilize a proven execution plan.

    Read guide →

  • Sep 14, 2026
    Guide

    Oracle SQL Tuning with AWR and ASH, Part 2: Diagnose with ASH and Runtime Plans

    Use ASH to classify database activity and runtime execution plans to find where the time went during a slow SQL execution.

    Read guide →

  • Sep 12, 2026
    Guide

    Oracle SQL Tuning with AWR and ASH, Part 1: Find and Prove the Regression

    Define the incident and use AWR evidence to identify the SQL, compare execution plans, and prove whether performance regressed.

    Read guide →

  • Jun 1, 2023
    Guide

    Fast Guide: PL/SQL

    PL/SQL is Oracle’s procedural extension to SQL. It lets you combine SQL statements with variables, conditions, loops, reusable subprograms, and exception handling. This quick guide covers the pieces…

    Read guide →

  • Feb 26, 2010
    Troubleshooting

    IMP-00017: Statement Failed with ORA-02304 During Schema Import

    An Oracle schema import can fail when object types are imported back into the same database under a different schema. The log commonly shows IMP-00017 together with ORA-02304:…

    Read guide →

  • Aug 11, 2007
    Troubleshooting

    ORA-19511 / NetBackup Status 25: Cannot Connect on Socket

    ORA-19511 is Oracle RMAN reporting an error returned by the media-management layer. When the accompanying NetBackup message is status 25: cannot connect on socket, troubleshoot the NetBackup connection…

    Read guide →

  • Aug 11, 2007
    Troubleshooting

    IBM TSM (ADSM) Backup: ANS1017E TCP/IP Connection Failure

    ANS1017E (RC-50) Session rejected: TCP/IP connection failure is a client-side message used by IBM Tivoli Storage Manager, now IBM Storage Protect. It tells you the session could not…

    Read guide →

  • May 11, 2007
    Troubleshooting

    ORA-01861: Using Date Formats in RMAN SET UNTIL TIME

    During point-in-time recovery, RMAN can report ORA-01861: literal does not match format string when the value supplied to SET UNTIL TIME does not match the session’s date format.…

    Read guide →

  • Feb 19, 2007
    Troubleshooting

    EXP-00003: No Storage Definition Found for Segment

    EXP-00003: no storage definition found for segment is raised by Oracle’s legacy Export utility when it cannot obtain the storage definition for a table, index, or cluster. On…

    Read guide →

  • Feb 12, 2007
    Guide

    Oracle Bind Variable Peeking and Plan Instability

    Bind variables improve cursor sharing, but a plan chosen for one bind value can perform poorly for another. Oracle calls the first-value optimization behavior bind variable peeking. How…

    Read guide →

1 2 3 4
Next Page→

Browse the library

Guides →

Step-by-step database administration and SQL tutorials.

Troubleshooting →

Error codes, backup failures, and recovery problems.

Looking for a specific error?

Use the search above with an error code such as ORA-01861 or a topic such as RMAN.

DBA Corner · You need your data back