.B "DELETE FROM ldap_entries WHERE id=?"
These four options specify SQL query templates for loading schema mapping
-metainformation,
-adding and deleting entries to ldap_entries, etc.
+metainformation, adding and deleting entries to ldap_entries, etc.
All these and subtree_cond should have the given default values.
For the current value it is recommended to look at the sources,
or in the log output when slapd starts with "-d 5" or greater.
if
.B upper_func
needs an explicit cast when applied to literal strings. The form
-.B cast (<arg> as varchar(<max DN length>))
+.B CAST (<arg> AS VARCHAR(<max DN length>))
is used, where
.B <max DN length>
is builtin.
MUST contain two question marks, '?', that will be replaced
by the two strings that must be concatenated. The default value is
.BR "CONCAT(?,?)";
-a form that is known to be highly portable is
+a form that is known to be highly portable (IBM db2, PostgreSQL) is
.BR "?||?",
but an explicit cast may be required when operating on literal strings:
-.BR "cast(?||? as varchar(<length>))".
-On some RDBMSes the form
+.BR "CAST(?||? AS VARCHAR(<length>))".
+On some RDBMSes (IBM db2, MSSQL) the form
.B "?+?"
is known to work.
Carefully check the documentation of your RDBMS or stay with the examples
.B fail_if_no_mapping { yes | no }
When set to
.B yes
-it forces write operations to fail if no appropriate mapping between LDAP
-attributes and SQL data is available. The default behavior is to ignore
-those changes that cannot be mapped correctly.
+it forces
+.I attribute
+write operations to fail if no appropriate mapping between LDAP attributes
+and SQL data is available.
+The default behavior is to ignore those changes that cannot be mapped
+correctly.
+It has no impact on objectClass mapping, i.e. if the
+.I structuralObjectClass
+of an entry cannot be mapped to SQL by looking up its name
+in ldap_oc_mappings, an
+.I add
+operation will fail regardless of the
+.B fail_if_no_mapping
+switch; see section "METAINFORMATION USED" for details.
This is
.B experimental
and may change in future releases.
The first thing that one must arrange is what set of LDAP
object classes can present your RDBMS information.
.LP
-The easiest way is to create an objectclass for each entity you had in
+The easiest way is to create an objectClass for each entity you had in
ER-diagram when designing your relational schema.
Any relational schema, no matter how normalized it is, was designed
after some model of your application's domain (for instance, accounts,
into the most relaxed SQL condition to filter candidates), and send it to
the user.
.LP
-ADD, DELETE, MODIFY operations are also performed on per-attribute
+ADD, DELETE, MODIFY and MODRDN operations are also performed on per-attribute
metainformation (add_proc etc.).
In those fields one can specify an SQL statement or stored procedure
call which can add, or delete given values of a given attribute, using
information on this matter - they are self-explanatory for those familiar
with concept expressed above.
.LP
-.SH common techniques (referrals, multiclassing etc.)
+.SH Common techniques (referrals, multiclassing etc.)
First of all, let's remember that among other major differences to the
complete LDAP data model, the concept above does not directly support
such things as multiple objectclasses per entry, and referrals.
values of "ref" attribute), you will have slapd return a referral, as
described in the Administrators Guide.
.LP
+.SH Caveats
+As previously stated, this backend should not be considered
+a replacement of other data storage backends, but rather a gateway
+to existing RDBMS storages that need to be published in LDAP form.
+.LP
+The hasSubordintes operational attribute is honored by back-sql
+in search results and in compare operations; it is partially honored
+also in filtering. Owing to design limitations, a (braindead) filter
+of the form
+\fB(!(hasSubordinates=TRUE))\fP
+will give no results instead of returning all the leaf entries.
+If you need to find all the leaf entries, please use
+\fB(hasSubordinates=FALSE)\fP
+instead.
+.LP
.SH EXAMPLES
There are example SQL modules in the slapd/back-sql/rdbms_depend/
directory in the OpenLDAP source tree.
projects / openldap / blobdiff