SELECT

Returns a result set from one or more data sources—tables, views, joined tables, and named subqueries.

Returns a result set from one or more data sources—tables, views, joined tables, and named subqueries.

Syntax

[ AT epoch ] [ WITH-clause ] SELECT [ ALL | DISTINCT ]
    { * | { MATCH_COLUMNS('pattern') | expression [ [AS] alias ] }[,...] }
    [ into-table-clause ]
    [ from-clause ]
    [ where-clause ]
    [ time-series-clause ]
    [ group-by-clause[,...] ]
    [ having-clause[,...] ]
    [ match-clause ]
    [ union-clause ]
    [ intersect-clause ]
    [ except-clause ]
    [ order-by-clause [ offset-clause ]]
    [ limit-clause ]
    [ FOR UPDATE [ OF table-name[,...] ] ]

Parameters

AT epoch
Returns data from the specified epoch, where epoch is one of the following:
  • EPOCH LATEST: Return data up to but not including the current epoch. The result set includes data from the latest committed DML transaction.

  • EPOCH integer: Return data up to and including the specified epoch.

  • TIME 'timestamp': Return data from the epoch at the specified timestamp.

These options are ignored if used to query temporary or external tables.

See Epochs for additional information about how Vertica uses epochs.

For details, see Historical queries.

ALL | DISTINCT
  • ALL (default): Retains duplicate rows in result set or group.

  • DISTINCT: Removes duplicate rows from the result set or group.

The ALL or DISTINCT qualifier must immediately follow the SELECT keyword. Only one instance of this keyword can appear in the select list.
*
Lists all columns in the queried tables.
MATCH_COLUMNS('pattern')
Returns all columns in the queried tables that match pattern.
expression [[AS] alias]
An expression that typically resolves to column data from the queried tables—for example, names of columns that are specified in the FROM clause; also:

You can optionally assign a temporary alias to each column expression and reference that alias elsewhere in the SELECT statement—for example, in the query predicate or ORDER BY clause. Vertica uses the alias as the column heading in query output.

FOR UPDATE
Specifies to obtain an X lock on all tables specified in the query, most often used from READ COMMITTED isolation.

FOR UPDATE requires update/delete permissions on the queried tables and cannot be issued from a read-only transaction.

Privileges

Non-superusers:

  • USAGE on the schema

  • SELECT on the table or view

Examples

When multiple clients run transactions as in the following example query, deadlocks can occur if FOR UPDATE is not used. Two transactions acquire an S lock, and when both attempt to upgrade to an X lock, they encounter deadlocks:

=> SELECT balance FROM accounts WHERE account_id=3476 FOR UPDATE;
    ...
=> UPDATE accounts SET balance = balance+10 WHERE account_id=3476;
=> COMMIT;

See also