Ubuntu Manpage: stilts-sqlskymatch - Crossmatches table on sky position against SQL table

NAME

       stilts-sqlskymatch - Crossmatches table on sky position against SQL table

SYNOPSIS

       stilts sqlskymatch [ifmt=<in-format>] [istream=true|false] [in=<table>] [icmd=<cmds>]
                          [ocmd=<cmds>]
                          [omode=out|meta|stats|count|checksum|cgi|discard|topcat|samp|tosql|gui]
                          [out=<out-table>] [ofmt=<out-format>] [ra=<expr>] [dec=<expr>]
                          [sr=<expr/deg>] [find=best|all|each] [usefoot=true|false]
                          [footnside=<int-value>] [copycols=<colid-list>] [scorecol=<col-name>]
                          [erract=abort|ignore|retry|retry<n>] [ostream=true|false]
                          [fixcols=none|dups|all] [suffix0=<label>] [suffix1=<label>] [db=<jdbc-
                          url>] [user=<value>] [password=<value>] [dbtable=<table-name>]
                          [dbra=<sql-col>] [dbdec=<sql-col>] [dbunit=deg|rad]
                          [tiling=hpx<K>|healpixnest<K>|healpixring<K>|htm<K>] [dbtile=<sql-col>]
                          [selectcols=<sql-cols>] [where=<sql-condition>] [preparesql=true|false]

DESCRIPTION

       sqlskymatch resembles coneskymatch, but instead of sending an HTTP query to a remote  cone
       search service for each match (i.e. each row of the input table), it executes an SQL query
       directly. The query is a SELECT statement with a WHERE clause which makes restrictions  on
       Right  Ascension  and  Declination  columns;  the  names of these columns must be given as
       parameters. The effect is that of a spatial join between a client-side table and  a  table
       stored in the database.

       This  command can only be used if you have access to an SQL database via JDBC. The details
       of how to configure a JDBC connection to a database are discussed in SUN/256  -  obviously
       you  will  need a database to connect to and appropriate read permissions on it as well as
       the relevant drivers.

       Note: this task was known as sqlcone in its experimental form in STILTS v1.3.

OPTIONS

ifmt=<in-format>
Specifies the format of the input table as specified by parameter in. The known
formats are listed in SUN/256. This flag can be used if you know what format your
table is in. If it has the special value (auto) (the default), then an attempt will
be made to detect the format of the table automatically. This cannot always be done
correctly however, in which case the program will exit with an error explaining
which formats were attempted. This parameter is ignored for scheme-specified
tables.

istream=true|false
If set true, the input table specified by the in parameter will be read as a
stream. It is necessary to give the ifmt parameter in this case. Depending on the
required operations and processing mode, this may cause the read to fail (sometimes
it is necessary to read the table more than once). It is not normally necessary to
set this flag; in most cases the data will be streamed automatically if that is the
best thing to do. However it can sometimes result in less resource usage when
processing large files in certain formats (such as VOTable). This parameter is
ignored for scheme-specified tables.

in=<table>
The location of the input table. This may take one of the following forms:

* A filename.

* A URL.

* The special value "-", meaning standard input. In this case the input format
must be given explicitly using the ifmt parameter. Note that not all formats
can be streamed in this way.

* A scheme specification of the form :<scheme-name>:<scheme-args>.

* A system command line with either a "<" character at the start, or a "|"
character at the end ("<syscmd" or "syscmd|"). This executes the given pipeline
and reads from its standard output. This will probably only work on unix-like
systems.
In any case, compressed data in one of the supported compression formats (gzip,
Unix compress or bzip2) will be decompressed transparently.

icmd=<cmds>
Specifies processing to be performed on the input table as specified by parameter
in, before any other processing has taken place. The value of this parameter is one
or more of the filter commands described in SUN/256. If more than one is given,
they must be separated by semicolon characters (";"). This parameter can be
repeated multiple times on the same command line to build up a list of processing
steps. The sequence of commands given in this way defines the processing pipeline
which is performed on the table.

Commands may alternatively be supplied in an external file, by using the
indirection character '@'. Thus a value of "@filename" causes the file filename to
be read for a list of filter commands to execute. The commands in the file may be
separated by newline characters and/or semicolons, and lines which are blank or
which start with a '#' character are ignored. A backslash character '\fR' at the
end of a line joins it with the following line.

ocmd=<cmds>
Specifies processing to be performed on the output table, after all other
processing has taken place. The value of this parameter is one or more of the
filter commands described in SUN/256. If more than one is given, they must be
separated by semicolon characters (";"). This parameter can be repeated multiple
times on the same command line to build up a list of processing steps. The sequence
of commands given in this way defines the processing pipeline which is performed on
the table.

omode=out|meta|stats|count|checksum|cgi|discard|topcat|samp|tosql|gui
The mode in which the result table will be output. The default mode is out, which
means that the result will be written as a new table to disk or elsewhere, as
determined by the out and ofmt parameters. However, there are other possibilities,
which correspond to uses to which a table can be put other than outputting it, such
as displaying metadata, calculating statistics, or populating a table in an SQL
database. For some values of this parameter, additional parameters (<mode-args>)
are required to determine the exact behaviour.

Possible values are

* out

* meta

* stats

* count

* checksum

* cgi

* discard

* topcat

* samp

* tosql

* gui
Use the help=omode flag or see SUN/256 for more information.

out=<out-table>
The location of the output table. This is usually a filename to write to. If it is
equal to the special value "-" (the default) the output table will be written to
standard output.

This parameter must only be given if omode has its default value of "out".

ofmt=<out-format>
Specifies the format in which the output table will be written (one of the ones in
SUN/256 - matching is case-insensitive and you can use just the first few letters).
If it has the special value "(auto)" (the default), then the output filename will
be examined to try to guess what sort of file is required usually by looking at the
extension. If it's not obvious from the filename what output format is intended, an
error will result.

This parameter must only be given if omode has its default value of "out".

ra=<expr>
Right ascension in degrees in the coordinate system for the position of each row of
the input table. This may simply be a column name, or it may be an algebraic
expression calculated from columns as explained in SUN/256. If left blank, an
attempt is made to guess from UCDs, column names and unit annotations what
expression to use.

dec=<expr>
Declination in degrees in the coordinate system for the position of each row of the
input table. This may simply be a column name, or it may be an algebraic expression
calculated from columns as explained in SUN/256. If left blank, an attempt is made
to guess from UCDs, column names and unit annotations what expression to use.

sr=<expr/deg>
Expression which evaluates to the search radius in degrees for the request at each
row of the input table. This will often be a constant numerical value, but may be
the name or ID of a column in the input table, or a function involving one.

find=best|all|each
Determines which matches are retained.

* best: Only the matching query table row closest to the input table row will be
output. Input table rows with no matches will be omitted. (Note this
corresponds to the best1 option in the pair matching commands, and best1 is a
permitted alias).

* all: All query table rows which match the input table row will be output. Input
table rows with no matches will be omitted.

* each: There will be one output table row for each input table row. If matches
are found, the closest one from the query table will be output, and in the case
of no matches, the query table columns will be blank.

usefoot=true|false
Determines whether an attempt will be made to restrict searches in accordance with
available footprint information. If this is set true, then before any of the per-
row queries are performed, an attempt may be made to acquire footprint information
about the servce. If such information can be obtained, then queries which fall
outside the footprint, and hence which are known to yield no results, are skipped.
This can speed up the search considerably.

Currently, the only footprints available are those provided by the CDS MOC (Multi-
Order Coverage map) service, which covers VizieR and a few other cone search
services.

footnside=<int-value>
Determines the HEALPix Nside parameter for use with the MOC footprint service. This
tuning parameter determines the resolution of the footprint if available. Larger
values give better resolution, hence a better chance of avoiding unnecessary
queries, but processing them takes longer and retrieving and storing them is more
expensive.

The value must be a power of 2, and at the time of writing, the MOC service will
not supply footprints at resolutions greater than nside=512, so it should be <=512.

Only used if usefoot=true.

copycols=<colid-list>
List of columns from the input table which are to be copied to the output table.
Each column identified here will be prepended to the columns of the combined output
table, and its value for each row taken from the input table row which provided the
parameters of the query which produced it. See SUN/256 for list syntax. The default
setting is "*", which means that all columns from the input table are included in
the output.

scorecol=<col-name>
Gives the name of a column in the output table to contain the distance between the
requested central position and the actual position of the returned row. The
distance returned is an angular distance in degrees. If a null value is chosen, no
distance column will appear in the output table.

erract=abort|ignore|retry|retry<n>
Determines what will happen if any of the individual cone search requests fails. By
default the task aborts. That may be the best thing to do, but for unreliable or
poorly implemented services you may find that some searches fail and others succeed
so it can be best to continue operation in the face of a few failures. The options
are:

* abort: Failure of any query terminates the task.

* ignore: Failure of a query is treated the same as a query which returns no
rows.

* retry: Failed queries are retried until they succeed; an increasing delay is
introduced for each failure. Use with care - if the failure is for some good,
or at least reproducible reason this could prevent the task from ever
completing.

* retry<n>: Failed queries are retried at most a fixed number <n> of times; an
increasing delay is introduced for each failure. If failures persist the task
terminates.

ostream=true|false
If set true, this will cause the operation to stream on output, so that the output
table is built up as the results are obtained from the cone search service. The
disadvantage of this is that some output modes and formats need multiple passes
through the data to work, so depending on the output destination, the operation may
fail if this is set. Use with care (or be prepared for the operation to fail).

fixcols=none|dups|all
Determines how input columns are renamed before use in the output table. The
choices are:

* none: columns are not renamed

* dups: columns which would otherwise have duplicate names in the output will be
renamed to indicate which table they came from

* all: all columns will be renamed to indicate which table they came from
If columns are renamed, the new ones are determined by suffix* parameters.

suffix0=<label>
If the fixcols parameter is set so that input columns are renamed for insertion
into the output table, this parameter determines how the renaming is done. It gives
a suffix which is appended to all renamed columns from the input table.

suffix1=<label>
If the fixcols parameter is set so that input columns are renamed for insertion
into the output table, this parameter determines how the renaming is done. It gives
a suffix which is appended to all renamed columns from the cone result table.

db=<jdbc-url>
URL which defines a connection to a database. This has the form
jdbc:<subprotocol>:<subname> - the details are database- and driver-dependent.
Consult Sun's JDBC documentation and that for the particular JDBC driver you are
using for details. Note that the relevant driver class will need to be on your
classpath and referenced in the jdbc.drivers system property as well for the
connection to be made.

user=<value>
User name for logging in to SQL database. Defaults to the current username.

password=<value>
Password for logging in to SQL database.

dbtable=<table-name>
The name of the table in the SQL database which provides the remote data.

dbra=<sql-col>
The name of a column in the SQL database table dbtable which gives the right
ascension. Units are given by dbunit.

dbdec=<sql-col>
The name of a column in the SQL database table dbtable which gives the declination.
Units are given by dbunit.

dbunit=deg|rad
Units of the right ascension and declination columns identified in the database
table. May be either deg[rees] (the default) or rad[ians].

tiling=hpx<K>|healpixnest<K>|healpixring<K>|htm<K>
Describes the sky tiling scheme that is in use. One of the following values may be
used:

* hpxK: alias for healpixnestK

* healpixnestK: HEALPix using the Nest scheme at order K

* healpixringK: HEALPix using the Ring scheme at order K

* htmK: Hierarchical Triangular Mesh at level K
So for instance hpx5 or healpixnest5 would both indicate the HEALPix NEST tiling
scheme at order 5.

At level K, there are 12*4^K HEALPix pixels, or 8*4^K HTM pixels on the sky. More
information about these tiling schemes can be found at the HEALPix and HTM web
sites.

dbtile=<sql-col>
The name of a column in the SQL database table dbtable which contains a sky tiling
pixel index. The tiling scheme is given by the tiling parameter. Use of a tiling
column is optional, but if present (and if the column is indexed in the database
table) it may serve to speed up searches. Set to null if the database table
contains no tiling column or if you do not wish to use one.

selectcols=<sql-cols>
An SQL expression for the list of columns to be selected from the table in the
database. A value of "*" retrieves all columns.

where=<sql-condition>
An SQL expression further limiting the rows to be selected from the database. This
will be combined with the constraints on position implied by the cone search
centres and radii. The value of this parameter should just be a condition, it
should not contain the WHERE keyword. A null value indicates no additional
criteria.

preparesql=true|false
If true, the JDBC connection will use PreparedStatements for the SQL SELECTs
otherwise it will use simple Statements. This is a tuning parameter and affects
only performance. On some database/driver combinations it's a lot faster set false
(the default); on others it may be faster, who knows?

VERSION

       STILTS version 3.5.1-debian

       This is the Debian version of Stilts, which lack the support  of  some  file  formats  and
       network protocols. For differences see
       file:///usr/share/doc/stilts/README.Debian

AUTHOR