# $OpenLDAP$ # Copyright 1999-2000, The OpenLDAP Foundation, All Rights Reserved. # COPYING RESTRICTIONS APPLY, see COPYRIGHT. H1: Database Creation and Maintenance Tools This section tells you how to create a slapd database from scratch, and how to do trouble shooting if you run into problems. There are two ways to create a database. First, you can create the database on-line using LDAP. With this method, you simply start up slapd and add entries using the LDAP client of your choice. This method is fine for relatively small databases (a few hundred or thousand entries, depending on your requirements). The second method of database creation is to do it off-line, using the index generation tools. This method is best if you have many thousands of entries to create, which would take an unacceptably long time using the LDAP method, or if you want to ensure the database is not accessed while it is being created. H2: Creating a database over LDAP With this method, you use the LDAP client of your choice (e.g., the ldapadd(1) tool) to add entries, just like you would once the database is created. You should be sure to set the following configuration options before starting slapd: E: suffix As described in the preceding section, this option says what entries are to be held by this database. You should set this to the DN of the root of the subtree you are trying to create. For example E: suffix "dc=OpenLDAP, dc=org" You should be sure to specify a directory where the index files should be created: E: directory For example: E: directory /usr/local/openldap/slapd You need to make it so you can connect to slapd as somebody with permission to add entries. This is done through the following two options in the database definition: E: rootdn E: rootpw These options specify a DN and password that can be used to authenticate as the "superuser" entry of the database (i.e., the entry allowed to do anything). The DN and password specified here will always work, regardless of whether the entry named actually exists or has the password given. This solves the chicken-and-egg problem of how to authenticate and add entries before any entries yet exist. Finally, you should make sure that the database definition contains the index definitions you want: E: index { | default} [pres,eq,approx,sub,none] For example, to index the cn, sn, uid and objectclass attributes the following index configuration lines could be used. E: index cn,sn,uid E: index objectclass pres,eq E: index default none See Section 4 on the configuration file for more details on this option. Once you have configured things to your liking, start up slapd, connect with your LDAP client, and start adding entries. For example, to add a the organizational entry followed by a Postmaster entry using the {{I:ldapadd}} tool, you could create a file called {{EX:/tmp/newentry}} with the contents: E: dc=OpenLDAP, dc=org E: objectClass=dcObject E: objectClass=organization E: dc=OpenLDAP E: o=OpenLDAP E: o=OpenLDAP Project E: o=OpenLDAP Foundation E: description=The OpenLDAP Foundation E: description=The OpenLDAP Project E: E: cn=Postmaster, dc=OpenLDAP, dc=org E: objectClass=organizationalRole E: cn=Postmaster E: description=OpenLDAP Postmaster and then use a command like this to actually create the entry: E: ldapadd -f /tmp/newentry -D "cn=Manager, dc=OpenLDAP, dc=org" -w secret The above command assumes that you have set {{EX: rootdn}} to "cn=Manager, dc=OpenLDAP, dc=org" and {{EX: rootpw}} to "secret". H2: Creating a database off-line The second method of database creation is to do it off-line, using the index generation tools described below. This method is best if you have many thousands of entries to create, which would take an unacceptably long time using the LDAP method described above. These tools read the slapd configuration file and an input file containing a text representation of the entries to add. They produce the LDBM index files directly. There are several important configuration options you will want to be sure and set in the config file database definition first: E: suffix As described in the preceding section, this option says what entries are to be held by this database. You should set this to the DN of the root of the subtree you are trying to create. For example E: suffix "dc=OpenLDAP, dc=org" You should be sure to specify a directory where the index files should be created: E: directory For example: E: directory /usr/local/var/openldap Next, you probably want to increase the size of the in-core cache used by each open index file. For best performance during index creation, the entire index should fit in memory. If your data is too big for this, or your memory too small, you can still make it pretty big and let the paging system do the work. This size is set with the following option: E: dbcachesize For example: E: dbcachesize 50000000 This would create a cache 50 MB big, which is pretty big (at U-M, our database has about 125K entries, and our biggest index file is about 45 MB). Experiment with this number a bit, and the degree of parallelism (explained below), to see what works best for your system. Remember to turn this number back down once your index files are created and before you run slapd. Finally, you need to specify which indexes you want to build. This is done by one or more index options. E: index { | default} [pres,eq,approx,sub,none] For example: E: index cn,sn,uid pres,eq,approx E: index default none This would create presence, equality and approximate indexes for the cn, sn, and uid attributes, and no indexes for any other attributes. See the configuration file section for more information on this option. H3: The {{EX: ldif2ldbm}} program Once you've configured things to your liking, you create the indexes by running the ldif2ldbm program: E: ldif2ldbm -i -f E: [-d ] [-j ] E: [-n ] [-e ] The arguments have the following meanings: E: -i Specifies the LDIF input file containing the entries to add in text form (described below in Section 8.3). E: -f Specifies the slapd configuration file that tells where to create the indexes, what indexes to create, etc. E: -d Turn on debugging, as specified by {{EX: }}. The debug levels are the same as for slapd (see Section 6.1). E: -j An optional argument that specifies that at most {{EX: }} processes should be started in parallel when building the indexes. The default is 1. If set to a value greater than one, {{I: ldif2ldbm}} will create at most that many subprocesses at a time when building the indexes. A separate subprocess is created to build each attribute index. Running these processes in parallel can speed things up greatly, but beware of creating too many processes, all competing for memory and disk resources. E: -n An optional argument that specifies the configuration file database for which to build indices. The first database listed is "1", the second "2", etc. By default, the first ldbm database in the configuration file is used. E: -e An optional argument that specifies the directory where {{EX: ldif2ldbm}} can find the other database conversion tools it needs to execute ({{EX: ldif2index}} and friends). The default is the installation {{EX: ETCDIR}}. The next sections describe the programs invoked by {{I: ldif2ldbm}} when it is building indexes. Normally, these programs are invoked for you, but occasionally you may want to invoke them yourself. H3: The {{EX: ldif2index}} program Sometimes it may be necessary to create a new attribute index file without disturbing the rest of the database. This is possible using the {{EX: ldif2index}} program. {{EX: ldif2index}} is invoked like this E: ldif2index -i -f E: [-d ] [-n ] Where the -i, -f, -d, and -n options are the same as for the {{I: ldif2ldbm}} program. {{EX: }} is the attribute to build an index for. Which indexes are built (e.g., equality, substring, etc.) is controlled by the corresponding index line in the slapd configuration file. You can use the ldbmcat program to create a suitable LDIF input file from an existing LDBM database. H3: The {{EX: ldbmcat}} program The {{EX: ldbmcat}} program is used to convert an {{EX: id2entry}} index back into its LDIF text format. This can be useful when you want to make a human-readable backup of your database, or as an intermediate step in creating a new index using the {{EX: ldif2index}} program. The program is invoked like this: E: ldbmcat [-n] where {{EX: }} is the name of the {{EX: id2entry}} index file. The corresponding LDIF output is written to standard output. The -n option can be used to prevent the printing of entry IDs in the LDIF format. If you are creating an LDIF format for use as input to {{EX: ldif2index}} or anything by {{EX: ldif2ldbm}}, you should not use the -n option (because the entry IDs must match those already in the id2entry file). If you are just making a backup of your data, you can use the -n option to save space. H3: The {{EX: ldif}} program The ldif program is used to convert arbitrary data values to LDIF format. This can be useful when writing a program or script to create the LDIF file you will feed into the ldif2ldbm program, or when writing a SHELL backend. ldif takes an attribute name as an argument, and reads the attribute value(s) from standard input. It produces the LDIF formatted attribute line(s) on standard output. The usage is: E: ldif [-b] where {{EX: }} is the name of the attribute. Without the -b option, ldif considers each line of standard input to be a separate value of the attribute. The -b option can be used to force ldif to interpret its input as a single raw binary value. This option is useful when converting binary data such as a {{EX: jpegPhoto}} or {{EX: audio}} attribute. H2: The LDIF text entry format The LDAP Data Interchange Format (LDIF) is used to represent LDAP entries in a simple text format. The basic form of an entry is: E: [] E: dn: E: : E: : E: E: ... where {{EX: }} is the optional entry ID (a positive decimal number). Normally, you would not supply the {{EX: }}, allowing the database creation tools to do that for you. The ldbmcat program, however, produces an LDIF format that includes {{EX: }} so that new indexes created will be consistent. A line may be continued by starting the next line with a single space or tab character. e.g., E: dn: cn=Barbara J Jensen, dc=OpenLDAP, dc=org Multiple attribute values are specified on separate lines. e.g., E: cn: Barbara J Jensen E: cn: Babs Jensen If an {{EX: }} contains a non-printing character, or begins with a space or a colon `:', the {{EX: }} is followed by a double colon and the value is encoded in base 64 notation. e.g., the value " begins with a space" would be encoded like this: E: cn:: IGJlZ2lucyB3aXRoIGEgc3BhY2U= Multiple entries within the same LDIF file are separated by blank lines. Here's an example of an LDIF file containing three entries. E: dn: cn=Barbara J Jensen, dc=OpenLDAP, dc=org E: cn: Barbara J Jensen E: cn: Babs Jensen E: objectclass: person E: sn: Jensen E: E: dn: cn=Bjorn J Jensen, dc=OpenLDAP, dc=org E: cn: Bjorn J Jensen E: cn: Bjorn Jensen E: objectclass: person E: sn: Jensen E: E: dn: cn=Jennifer J Jensen, dc=OpenLDAP, dc=org E: cn: Jennifer J Jensen E: cn: Jennifer Jensen E: objectclass: person E: sn: Jensen E: jpegPhoto:: /9j/4AAQSkZJRgABAAAAAQABAAD/2wBDABALD E: A4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdASFxOQ E: ERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVG E: E: ... Notice that the {{EX: jpegPhoto}} in Jennifer Jensen's entry is encoded using base 64. The {{EX: ldif}} program (described in Section 8.2.6) can be used to produce the LDIF format. Note: Trailing spaces are not trimmed from values in an LDIF file. Nor are multiple internal spaces compressed. If you don't want them in your data, don't put them there. H2: The LDBM database format In normal operation, it is not necessary for you to know much about the LDBM database format. If you are going to use the ldbmtest program to look at or alter the database, or if you want a deeper understanding of how indexes are maintained, some knowledge of how it works could be useful. This section gives an overview of the database format and how slapd makes use of it. H3: Overview The LDBM database works by assigning a compact four-byte unique identifier to each entry in the database. It uses this identifier to refer to entries in indexes. The database consists of one main index file, called id2entry, which maps from an entry's unique identifier (EID) to a text representation of the entry itself. Other index files are maintained, for each indexed attribute for example, that map values people are likely to search on to lists of EIDs. Using this simple scheme, many LDAP queries can be answered efficiently. For example, to answer a search for entries with a surname of "Jensen", slapd would first consult the surname attribute index, look up the value "Jensen" and retrieve the corresponding list of EIDs. Next, slapd would look up each EID in the id2entry index, retrieve the corresponding entry, convert it from text to LDAP format, and return it to the client. The following sections give a very brief overview of each type of index and what it contains. For more detailed information see the paper "An X.500 and LDAP Database: Design and Implementation," available in postscript format from {{URL:ftp://terminator.rs.itd.umich.edu/ldap/papers/xldbm.ps}} H3: Attribute index format The LDBM backend will maintain one index file for each attribute it is asked to index. Several sets of keys must coexist in this file (e.g., keys for equality and approximate equality), so the keys are prefixed with a character to ensure uniqueness. The prefixes are given in the table below E: = equality keys E: ~ approximate equality keys E: * substring equality keys E: \ continuation keys Key values are also normalized (e.g., converted to upper case for case ignore attributes). So, for example, to look up the surname equality value in the example above using the ldbmtest program, you would look up the value "{{EX: =JENSEN}}". Substring indexes are maintained by generating all possible N-character substrings for a value (N is 3 by default). These substrings are then stored in the attribute index, prefixed by "*". Additional anchors of "^" and "$" are added at the beginning and end of words. So, for example the surname of Jensen would cause the following keys to be entered in the index: {{EX: ^JE, JEN, ENS, NSE, SEN, EN$}}. Approximate values are handled in a similar way, with phonetic codes being generated for each word in a value and then stored in the index, prefixed by "~". Large blocks in the index are split into smaller ones. The smaller blocks are accessed through a level of indirection provided by the original block. They are stored in the index using the continuation key prefix of "\". H3: Other indexes In addition to the {{EX: id2entry}} and attribute indexes, LDBM maintains a number of other indexes, including the {{EX: dn2id}} index and the {{EX: id2children}} index. These indexes provide the mapping between a DN and the corresponding EID, and the mapping between an EID and the EIDs of the corresponding entry's children, respectively. The {{EX: dn2id}} index stores normalized DNs as keys. The data stored is the corresponding EID. The {{EX: id2children}} index stores EIDs as keys. The data stored is a list of EIDs, just as for the attribute indexes.