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.TH mg_perf_hash_build 1 \*(Dt CITRI
.SH NAME
mg_perf_hash_build \- generate an order-preserving hash function for the stemmed dictionary
.SH SYNOPSIS
.B mg_perf_hash_build
[
.B \-h
]
[
.BI \-r " rndseed"
]
[
.BI \-d  " directory"
]
.if n .ti +9n
.BI \-f " name"
.SH DESCRIPTION
.B mg_perf_hash_build
generates an order-preserving hashing function from the compressed
stemmed dictionary and writes it out to disk.
.BR mg_passes (1)
will make use of the hash function when it builds the inverted file.
.SH OPTIONS
Options may appear in any order.
.TP "\w'\fB\-d\fP \fIdirectory\fP'u+2n"
.B \-h
This displays a usage line on
.IR stderr .
.TP
.BI \-r " rndseed"
This specifies the random seed to be used in the generation of the
hash function; it must be an integer.  If this is not specified, the
current time will be used as the random seed.
.TP
.BI \-d " directory"
This specifies the directory where the document collection can be found.
.TP
.BI \-f " name"
This specifies the base name of the document collection.
.SH ENVIRONMENT
.TP "\w'\fBMGDATA\fP'u+2n"
.SB MGDATA
If this environment variable exists, then its value is used as the
default directory where the mg
collection files are.  If this variable does not exist, then the
directory \*(lq\fB.\fP\*(rq is used by default.  The command line
option
.BI \-d " directory"
overrides the directory in
.BR MGDATA .
.SH FILES
.TP 20
.B *.invf.dict
Stemmed dictionary.
.TP
.B *.invf.dict.hash
Data for a order-preserving perfect hash function.
.SH "SEE ALSO"
.na
.BR mg_compression_dict (1),
.BR mg_fast_comp_dict (1),
.BR mg_invf_dict (1),
.BR mg_passes (1),
.BR mg_stem_idx (1),
.BR mg_weights_build (1)