The iquery executable is the basic command-line tool for communicating with SciDB. Use iquery to issue Array Functional Language (AFL) commands and also queries for the prototype Array Query Language (AQL).

It is installed into /opt/scidb/<version>/bin.

Starting iquery

To start iquery for AQL (the default), do the following:

1. Type iquery -a at the command line in an active SciDB session. iquery opens an AFL% command prompt.
2. Enter AFL queries at the command prompt.

Using iquery

To view the iquery commands reference, type help; at the AFL prompt. The commands appear.

set            - List current options
set lang afl   - Set AFL as querying language
set lang aql   - Set AQL as querying language
set fetch      - Start retrieving query results
set no fetch   - Stop retrieving query results
set timer      - Start reporting query setup time
set no timer   - Stop reporting query setup time
set verbose    - Start reporting details from engine
set no verbose - Stop reporting details from engine
set format <base_format> [ :<options> ] - Switch output format
quit or exit   - End iquery session-

Available base_format values are:
csv     - Comma separated values
csv+    - Comma separated values including coordinates
dcsv    - "Display CSV", a more human-readable CSV variant
dense   - A variant of 'text' suitable for dense data
sparse  - A variant of 'text' suitable for sparse data
opaque  - SciDB raw storage format
store   - A variant of 'text' that includes overlap regions
text    - SciDB native text format
tsv     - Tab separated values (LinearTSV dialect)
tsv+    - Tab separated values including coordinates (LinearTSV)

Option flags for modifying output format.  Not all flags affect all
formats.  These may be combined:
d - Use double quotes in CSV output
E - Use an empty string for null in TSV or CSV output
l - Print label line for TSV or CSV output
N - Use \N for null in CSV output
n - Use the unquoted token 'null' for null in TSV or CSV output
s - Use single quotes in CSV output (normally the default)
? - Use ?0 for null in TSV or CSV output

To pass an AFL query directly to iquery from the command line, use the -aq flag:

iquery -aq "my AFL statement"

You can also pass a file containing an AFL query to iquery with the -f flag:

iquery -af my_input_filename

Each invocation of iquery connects to a SciDB instance, which becomes the query coordinator, passes in a query string, and prints out the instance's response. iquery connects by default to SciDB on port 1239. To use a port number other than the default, specify it using the -p option with iquery. For example, to use port 9999 to run an AFL query contained in the file my_filename do this:

iquery -af my_input_filename -p 9999

The query result prints to stdout. Use -r flag to redirect the output to a file:

iquery -r my_output_filename -af my_input_filename 

To change the output format, use the -o flag:

iquery -o csv -r my_output_filename.csv -af my_input_filename 

Reserved Words

 SciDB reserves certain keywords that you cannot use as identifiers (such as array names, dimension names, or attribute names). The lists are language-dependent.

AFL

The following words are reserved when using AFL.

AQL

All the AFL reserved words are also reserved in AQL - which is SciDB's prototype query language. In addition, AQL also reserves the following words.

Output Formats

Available output formats are described in the following table:

iquery Switches

To view a list of the iquery switches and their descriptions, type iquery -h or iquery --help at the command line. The switches are explained in the following table: