(OpenLDAP FAQ-O-Matic/General LDAP FAQ/Directories vs. conventional
databases) to find out more on this point.
.LP
-The idea (detailed below) is to use some metainformation to translate
+The idea (detailed below) is to use some meta-information to translate
LDAP queries to SQL queries, leaving relational schema untouched, so
that old applications can continue using it without any
modifications.
replication, and exchange data as needed.
.LP
The SQL backend is designed to be tunable to virtually any relational
-schema without having to change source (through that metainformation
+schema without having to change source (through that meta-information
mentioned).
Also, it uses ODBC to connect to RDBMSes, and is highly configurable
for SQL dialects RDBMSes may use, so it may be used for integration
.RE
.SH STATEMENT CONFIGURATION
These options specify SQL query templates for loading schema mapping
-metainformation, adding and deleting entries to ldap_entries, etc.
+meta-information, 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.
keys - he may want to write a patch, and submit it to OpenLDAP ITS,
then I'll include it.
.LP
-Also, several people complained that they don't really need very
+Also, several users complained that they don't really need very
structured trees, and they don't want to update one more table every
time they add or delete an instance in the relational schema.
Those people can use a view instead of a real table for ldap_entries, something
directive for a possible workaround.
.LP
-.SH Typical SQL backend operation
-Having metainformation loaded, the SQL backend uses these tables to
+.SH TYPICAL SQL BACKEND OPERATION
+Having meta-information loaded, the SQL backend uses these tables to
determine a set of primary keys of candidates (depending on search
scope and filter).
It tries to do it for each objectclass registered in ldap_objclasses.
the user.
.LP
ADD, DELETE, MODIFY and MODRDN operations are also performed on per-attribute
-metainformation (add_proc etc.).
+meta-information (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
the given entry keyval (see examples -- mostly PostgreSQL, ORACLE and MSSQL
information on this matter - they are self-explanatory for those familiar
with the concepts expressed above.
.LP
-.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.
+.SH COMMON TECHNIQUES
+First of all, let's recall that among other major differences to the
+complete LDAP data model, the above illustrated concept does not directly
+support such features as multiple objectclasses per entry, and referrals.
Fortunately, they are easy to adopt in this scheme.
-The SQL backend suggests one more table being added to the schema:
+The SQL backend requires that one more table is added to the schema:
ldap_entry_objectclasses(entry_id,oc_name).
.LP
-The first contains any number of objectclass names that corresponding
-entries will be found by, in addition to that mentioned in
-mapping.
+That table contains any number of objectclass names that corresponding
+entries will possess, in addition to that mentioned in mapping.
The SQL backend automatically adds attribute mapping for the "objectclass"
attribute to each objectclass mapping that loads values from this table.
So, you may, for instance, have a mapping for inetOrgPerson, and use it
an "extensibleObject" value to ldap_entry_objclasses.
.LP
-.SH Caveats
+.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.
instead.
.LP
A directoryString value of the form "__First___Last_"
-(where underscores should be replaced by spaces) corresponds
+(where underscores mean spaces, ASCII 0x20 char) corresponds
to its prettified counterpart "First_Last"; this is not currently
honored by back-sql if non-prettified data is written via RDBMS;
when non-prettified data is written thru back-sql, the prettified
values are actually used instead.
+
+.LP
+.SH BUGS
+When the
+.B ldap_entry_objclasses
+table is empty, filters on the
+.B objectClass
+attribute erroneously result in no candidates.
+A workaround consists in adding at least one row to that table,
+no matter if valid or not.
+
.LP
.SH PROXY CACHE OVERLAY
The proxy cache overlay