Monitoring the Log Files
When a Database is Running
When a Vertica database is running, each 
node in the cluster writes messages into a file named vertica.log. For example, the Tuple Mover and the transaction manager write INFO messages into vertica.log at specific intervals even when there is no WOS activity.
The tuple mover is the component of Vertica that moves the contents of the Write Optimized Store (WOS) into the Read Optimized Store (ROS). This data movement is known as a moveout. Normally, the tuple mover runs automatically in the background at preset intervals and is referred to as the ATM.
The ROS (Read Optimized Store) is a highly optimized, read-oriented, physical storage structure that is organized by projection and that makes heavy use of compression and indexing. You can use the COPY...DIRECT and INSERT (with direct hint) statements to load data directly into the ROS.
Compression is the process of transforming data into a more compact format. Compressed data cannot be directly processed; it must first be decompressed. Vertica uses integer packing for unencoded integers and LZO for compressible data. Although compression is generally considered to be a form of encoding, the terms have different meanings in Vertica.
LZO is an abbreviation for Lempel-Ziv-Oberhumer. It is a data compression algorithm that is focused on decompression speed. The algorithm is lossless and the reference implementation is thread safe.
The WOS (Write Optimized Store) is a memory-resident data structure into which INSERT, UPDATE, DELETE, and COPY (without DIRECT hint) actions are recorded. Like the ROS, the WOS is arranged by projection but it stores tuples without sorting, compression, or indexing and thus supports very fast load speeds. The WOS organizes data by epoch and holds uncommitted transaction data.
Compression is the process of transforming data into a more compact format. Compressed data cannot be directly processed; it must first be decompressed. Vertica uses integer packing for unencoded integers and LZO for compressible data. Although compression is generally considered to be a form of encoding, the terms have different meanings in Vertica.
LZO is an abbreviation for Lempel-Ziv-Oberhumer. It is a data compression algorithm that is focused on decompression speed. The algorithm is lossless and the reference implementation is thread safe.
The ROS (Read Optimized Store) is a highly optimized, read-oriented, physical storage structure that is organized by projection and that makes heavy use of compression and indexing. You can use the COPY...DIRECT and INSERT (with direct hint) statements to load data directly into the ROS.
Compression is the process of transforming data into a more compact format. Compressed data cannot be directly processed; it must first be decompressed. Vertica uses integer packing for unencoded integers and LZO for compressible data. Although compression is generally considered to be a form of encoding, the terms have different meanings in Vertica.
LZO is an abbreviation for Lempel-Ziv-Oberhumer. It is a data compression algorithm that is focused on decompression speed. The algorithm is lossless and the reference implementation is thread safe.
A cluster generally refers a collection of hosts or a collection of nodes bound to a database. A cluster is not part of a database definition and thus does not have a name.
A node is a host configured to run an instance of Vertica. It is a member of a database cluster (see Node Definition). For a database to have the ability to recover from the failure of a node requires at least three nodes. Vertica Systems, Inc. recommends that you use a minimum of four nodes.
A cluster generally refers a collection of hosts or a collection of nodes bound to a database. A cluster is not part of a database definition and thus does not have a name.
An instance of Vertica consists of the running Vertica process and disk storage (catalog and data) on a host. There can be only one instance of Vertica running on a host at any time.
To monitor a running database in real time:
- Log into the database administrator account on any or all of the nodes in the cluster.
- Enter:
$ tail -f catalog-path/database-name/node-name_catalog/vertica.log
When No Database is Running
When no database is running, each node in the cluster writes messages into a file named dbLog. For example, if a database fails to start before it can write messages into vertica.log, check the file:
catalog-path/database-name/dbLog
where catalog-path and database-name are as described above.
See Also
