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SELECT

Synopsis

SELECT
    [ CONSISTENT ]
    attributes
    FROM tablename
    [ KEYS IN primary_keys | WHERE expression ]
    [ USING index ]
    [ LIMIT limit ]
    [ SCAN LIMIT scan_limit ]
    [ ORDER BY field ]
    [ ASC | DESC ]
    [ THROTTLE throughput ]
    [ SAVE filename]

Examples

SELECT * FROM foobars SAVE out.p;
SELECT * FROM foobars WHERE foo = 'bar';
SELECT count(*) FROM foobars WHERE foo = 'bar';
SELECT id, TIMESTAMP(updated) FROM foobars KEYS IN 'id1', 'id2';
SELECT * FROM foobars KEYS IN ('hkey', 'rkey1'), ('hkey', 'rkey2');
SELECT CONSISTENT * foobars WHERE foo = 'bar' AND baz >= 3;
SELECT * foobars WHERE foo = 'bar' AND attribute_exists(baz);
SELECT * foobars WHERE foo = 1 AND NOT (attribute_exists(bar) OR contains(baz, 'qux'));
SELECT 10 * (foo - bar) FROM foobars WHERE id = 'a' AND ts < 100 USING ts-index;
SELECT * FROM foobars WHERE foo = 'bar' LIMIT 50 DESC;
SELECT * FROM foobars THROTTLE (50%, *);

Description

Query a table for items.

Parameters

CONSISTENT
If this is present, perform a strongly consistent read
attributes
Comma-separated list of attributes to fetch or expressions. You can use the TIMESTAMP and DATE functions, as well as performing simple, arbitrarily nested arithmetic (foo + (bar - 3) / 100). SELECT * is a special case meaning 'all attributes'. SELECT count(*) is a special case that will return the number of results, rather than the results themselves.
tablename
The name of the table
index
When the WHERE expression uses an indexed attribute, this allows you to manually specify which index name to use for the query. You will only need this if the constraints provided match more than one index.
limit
The maximum number of items to return.
scan_limit
The maximum number of items for DynamoDB to scan (not necessarily the number of matching items returned).
ORDER BY
Sort the results by a field.

Warning

Using ORDER BY with LIMIT may produce unexpected results. If you use ORDER BY on the range key of the index you are querying on, it will work as expected. Otherwise, DQL will fetch the number of results specified by the LIMIT and then sort them.

ASC | DESC
Sort the results in ASCending (the default) or DESCending order.
THROTTLE
Limit the amount of throughput this query can consume. This is a pair of values for (read_throughput, write_throughput). You can use a flat number or a percentage (e.g. 20 or 50%). Using * means no limit (typically useless unless you have set a default throttle in the :ref:`options`).
SAVE
Save the results to a file. By default the items will be encoded with pickle, but the '.json' and '.csv' extensions will use the proper format. You may also append a '.gz' or '.gzip' afterwards to gzip the results. Note that the JSON and CSV formats will be lossy because they cannot properly encode some data structures, such as sets.

Where Clause

If provided, the SELECT operation will use these constraints as the KeyConditionExpression if possible, and if not (or if there are constraints left over), the FilterExpression. All query syntax is pulled directly from the AWS docs: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html

In general, you may use any syntax mentioned in the docs, but you don't need to worry about reserved words or passing in data as variables like :var1. DQL will handle that for you.

Notes

When using the KEYS IN form, DQL will perform a batch get instead of a table query. See the AWS docs for more information on query parameters.