Some notes on the use of BLOBs (TEXT and BYTE columns):
BLOBs are normally addressed by BLOB identifiers. Select queries
return a "blob id" for every BYTE and TEXT column. You can get
at the contents with "string_var = ifx_get_blob($blob_id);" if
you choose to get the BLOBs in memory (with :
"ifx_blobinfile(0);"). If you prefer to receive the content of
BLOB columns in a file, use "ifx_blobinfile(1);", and
"ifx_get_blob($blob_id);" will get you the filename. Use normal
file I/O to get at the blob contents.
For insert/update queries you must create these "blob id's"
yourself with "ifx_create_blob();". You then
plug the blob id's into an array, and replace the blob columns
with a question mark (?) in the query string. For
updates/inserts, you are responsible for setting the blob
contents with ifx_update_blob().
The behaviour of BLOB columns can be altered by configuration
variables that also can be set at runtime :
configuration variable : ifx.textasvarchar
configuration variable : ifx.byteasvarchar
runtime functions :
ifx_textasvarchar(0) : use blob id's for select queries with TEXT
columns
ifx_byteasvarchar(0) : use blob id's for select queries with BYTE
columns
ifx_textasvarchar(1) : return TEXT columns as if they were
VARCHAR columns, so that you don't need to use blob id's for
select queries.
ifx_byteasvarchar(1) : return BYTE columns as if they were
VARCHAR columns, so that you don't need to use blob id's for
select queries.
configuration variable : ifx.blobinfile
runtime function :
ifx_blobinfile_mode(0) : return BYTE columns in memory, the blob
id lets you get at the contents.
ifx_blobinfile_mode(1) : return BYTE columns in a file, the blob
id lets you get at the file name.
If you set ifx_text/byteasvarchar to 1, you can use TEXT and BYTE
columns in select queries just like normal (but rather long)
VARCHAR fields. Since all strings are "counted" in PHP, this
remains "binary safe". It is up to you to handle this
correctly. The returned data can contain anything, you are
responsible for the contents.
If you set ifx_blobinfile to 1, use the file name returned by
ifx_get_blob(..) to get at the blob contents. Note that in this
case YOU ARE RESPONSIBLE FOR DELETING THE TEMPORARY FILES CREATED
BY INFORMIX when fetching the row. Every new row fetched will
create new temporary files for every BYTE column.
The location of the temporary files can be influenced by the
environment variable "blobdir", default is "." (the current
directory). Something like : putenv(blobdir=tmpblob"); will ease
the cleaning up of temp files accidentally left behind (their
names all start with "blb").
