73 lines
2.6 KiB
Plaintext
73 lines
2.6 KiB
Plaintext
# @(#)README 8.1 (Berkeley) 6/4/93
|
|
|
|
This package implements a superset of the hsearch and dbm/ndbm libraries.
|
|
|
|
Test Programs:
|
|
All test programs which need key/data pairs expect them entered
|
|
with key and data on separate lines
|
|
|
|
tcreat3.c
|
|
Takes
|
|
bucketsize (bsize),
|
|
fill factor (ffactor), and
|
|
initial number of elements (nelem).
|
|
Creates a hash table named hashtest containing the
|
|
keys/data pairs entered from standard in.
|
|
thash4.c
|
|
Takes
|
|
bucketsize (bsize),
|
|
fill factor (ffactor),
|
|
initial number of elements (nelem)
|
|
bytes of cache (ncached), and
|
|
file from which to read data (fname)
|
|
Creates a table from the key/data pairs on standard in and
|
|
then does a read of each key/data in fname
|
|
tdel.c
|
|
Takes
|
|
bucketsize (bsize), and
|
|
fill factor (ffactor).
|
|
file from which to read data (fname)
|
|
Reads each key/data pair from fname and deletes the
|
|
key from the hash table hashtest
|
|
tseq.c
|
|
Reads the key/data pairs in the file hashtest and writes them
|
|
to standard out.
|
|
tread2.c
|
|
Takes
|
|
butes of cache (ncached).
|
|
Reads key/data pairs from standard in and looks them up
|
|
in the file hashtest.
|
|
tverify.c
|
|
Reads key/data pairs from standard in, looks them up
|
|
in the file hashtest, and verifies that the data is
|
|
correct.
|
|
|
|
NOTES:
|
|
|
|
The file search.h is provided for using the hsearch compatible interface
|
|
on BSD systems. On System V derived systems, search.h should appear in
|
|
/usr/include.
|
|
|
|
The man page ../man/db.3 explains the interface to the hashing system.
|
|
The file hash.ps is a postscript copy of a paper explaining
|
|
the history, implementation, and performance of the hash package.
|
|
|
|
"bugs" or idiosyncracies
|
|
|
|
If you have a lot of overflows, it is possible to run out of overflow
|
|
pages. Currently, this will cause a message to be printed on stderr.
|
|
Eventually, this will be indicated by a return error code.
|
|
|
|
If you are using the ndbm interface and exit without flushing or closing the
|
|
file, you may lose updates since the package buffers all writes. Also,
|
|
the db interface only creates a single database file. To avoid overwriting
|
|
the user's original file, the suffix ".db" is appended to the file name
|
|
passed to dbm_open. Additionally, if your code "knows" about the historic
|
|
.dir and .pag files, it will break.
|
|
|
|
There is a fundamental difference between this package and the old hsearch.
|
|
Hsearch requires the user to maintain the keys and data in the application's
|
|
allocated memory while hash takes care of all storage management. The down
|
|
side is that the byte strings passed in the ENTRY structure must be null
|
|
terminated (both the keys and the data).
|