Reading a Database From a File in Small Chunks (lkt_open_dbfile)

The dbread command reads an entire database file, but there might be times when it is desirable to open a file and only read a handful of records at a time.
dvkerr_t lkt_open_dbfile( lpar_t file, lpar_t parameters, 
                          lpar_t *filehandle, lpar_t *dbpars );

lkt_open_dbfile is called like lkt_dbread but instead of reading records, it creates a special block lpar called a file handle. The contents of this lpar must never be altered directly, but can be passed to lkt_read_records to do the actual reading.

The input lpars for lkt_open_dbfile are identical to those of lkt_dbread, with the exception is that LPAR_INT_BATCHSIZE is not supported.

Open files are closed when the associated file handle lpar is destroyed with lpar_destroy.

Input

host file (required)

is the name of a file from which the database should be read. This must be either an LPAR_STR_CSVFILE or an LPAR_STR_FWFFILE for comma separated value or fixed width field files respectively.

parameters (optional)

is a list of parameters which describe the file contents. It might contain any of the following lpars (see Reading a Database From a File (lkt_dbread) for descriptions):

•

LPAR_STR_ENCODING

•

LPAR_INTARR_RECSRCHFLDS

•

LPAR_INT_DBNUMFIELDS

•

LPAR_BOOL_LEADINGKEY

•

LPAR_INT_KEYFIELD

•

LPAR_STR_KEYFIELD

•

LPAR_INT_INITIALKEY

•

LPAR_BOOL_FNAMESFIRST

•

LPAR_BOOL_FTYPESFIRST

•

LPAR_BOOL_DOMAXWORK

•

LPAR_INT_PARENT_KEYFIELD

•

LPAR_STR_PARENT_KEYFIELD

Output

filehandle (required)

is an opaque block lpar to be used with lkt_read_records.

dbpars (optional)

is a list of database parameters determined from reading the file. These parameters are intended to be passed to the lkt_dbload command as the dbpars parameter. Extra parameters can be added to the list as necessary.

 

Error codes and items returned by lkt_open_dbfile

ARRAYLEN	item that has the wrong length
EXPECTLIST	item that should have been a list type lpar
FILEFORMAT	a line from the file which could not be parsed
IOERROR	LPAR_STR_SYSERROR describing error
PARAMVAL	lpar that contains an illegal value
PARAMCONFLICT	lpar in conflict with an earlier lpar