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.TH mg_invf_rebuild 1 \*(Dt CITRI
.SH NAME
mg_invf_rebuild \- Rebuild an mg inverted file with or without skips.
.SH SYNOPSIS
.B mg_invf_rebuild
.RB [ \-h ]
.if n .ti +9n
[
.BR \-0 " |"
.B \-1
[
.BI \-k " num"
] |
.B \-2
[
.BI \-s " num"
]
[
.BI \-m " num"
]
]
.if n .ti +9n
[
.BI \-d " directory"
]
.BI \-f " name"
.SH DESCRIPTION
.B mg_invf_rebuild
builds a new inverted file, with or without skipping, from an old
inverted file.  This file uses
.I *.invf.ORG
and
.I *.invf.idx.ORG
as the
source from which it builds
.I *.invf
and
.IR *.invf.idx .
If
.I *.invf.ORG
or
.I *.invf.idx.ORG
do not exist, the program renames
.I *.invf
or
.I *.invf.idx
to
.I *.invf.ORG
or
.I *.invf.idx.ORG
as appropriate.  The old inverted file may contain skipping.  This
means that it is possible to delete the
.I *.ORG
files
after the new inverted file is built.
.SH OPTIONS
Options may appear in any order.
.TP "\w'\fB\-m\fP \fInum\fP'u+2n"
.B \-h
This displays a usage line on
.IR stderr .
.TP
.B \-0
This generates a non-skipped inverted file.  This option is normally
only needed if the
.I *.ORG
files have been deleted.
.TP
.B \-1
This generates a skipped inverted file.  The
.BI \-k " num"
argument specifies the number of pointers hopped over with each skip.
.TP
.B \-2
This option generates a skipped inverted file.  The skipped inverted
file is built so that it is `optimal' for ranking using a specific
number of accumulators.  Each term in the inverted file has a
different skip length.  The arguments
.BR \-s " and " \-m
control the sizes of the skips.
.TP
.BI \-k " num"
This specifies the number of pointers that should be hopped over with
each skip.  This option is only valid if
.B \-1
is specified.
.TP
.BI \-m " num"
This specifies the intended number of accumulators that will be used
when ranking queries are done on the collection.
.TP
.BI \-s " num"
This specifies the minimum size for skips.  If the calculation of the
optimal skip size results in a number smaller than
.IR num ,
the skip size is set to
.IR num .
.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
.BR mg (1)
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
Inverted file.
.TP
.B *.invf.ORG
Original inverted file.
.TP
.B *.invf.idx
The index into the inverted file.
.TP
.B *.invf.idx.ORG
The original index into the inverted file.
.TP
.B *.invf.dict.build
Compressed stemmed dictionary.
.SH "SEE ALSO"
.na
.BR mg (1),
.BR mg_compression_dict (1),
.BR mg_fast_comp_dict (1),
.BR mg_get (1),
.BR mg_invf_dict (1),
.BR mg_invf_dump (1),
.BR mg_passes (1),
.BR mg_perf_hash_build (1),
.BR mg_text_estimate (1),
.BR mg_weights_build (1),
.BR mgbilevel (1),
.BR mgbuild (1),
.BR mgdictlist (1),
.BR mgfelics (1),
.BR mgquery (1),
.BR mgstat (1),
.BR mgtic (1),
.BR mgticbuild (1),
.BR mgticdump (1),
.BR mgticprune (1),
.BR mgticstat (1).