15.00 - Locks and Concurrency - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

prodname
Teradata Database
vrm_release
15.00
category
Programming Reference
featnum
B035-1184-015K

Locks and Concurrency

When you do not specify the SPOOL, TEMP, or PERM options, MODIFY USER places an ACCESS lock on the database being altered and thus runs concurrently with all DML requests.

This is not true when you specify the SPOOL, TEMP, and PERM options because they all require an EXCLUSIVE lock.

This statement also places a rowhash‑level WRITE lock on the database for DBC.DBase. The SPOOL, TEMP, and PERM options then place a second lock on the immediate parent for DBC.DBase. For PERM, the second lock is a rowhash‑level WRITE lock. For SPOOL or TEMP, the second lock is a rowhash‑level READ lock.

The SPOOL, TEMP, and PERM options also place a rowhash‑level WRITE lock on DBC.DataBaseSpace. The PERM option then places a second rowhash‑level WRITE lock on the immediate parent for DBC.DataBaseSpace.

Related Topics

See “Activating Permanent Journaling” on page 43 for information about activating permanent journaling for existing tables.

Also see the following topics in this book.

  • “ALTER TABLE (Basic Table Parameters)” on page 31
  • “ALTER TABLE” in SQL Data Definition Language Syntax and Examples
  • “CREATE DATABASE” on page 225
  • “CREATE DATABASE” in SQL Data Definition Language Syntax and Examples
  • “MODIFY DATABASE” on page 827
  • “MODIFY DATABASE” in SQL Data Definition Language Syntax and Examples
  • “MODIFY USER” on page 831
  • “MODIFY USER” in SQL Data Definition Language Syntax and Examples