ASE originates in the mid 1980's from Bob Epstein's home in Berkeley, California. It was originally marketed as Sybase SQL Server for unix platforms, and it was the first DBMS to use a client-server architecture, which contrasted from other DBMSs in the market that were monolithic. It was Sybase's innovative client-server architecture and support for OLTP workloads that made their SQL server product popular on Wall Street in the early 1990's. In 1988, Sybase, Microsoft, and Ashton-Tate co-developed a SQL version for PC. In 1993, the co-development licensing agreement terminated, and Sybase and Microsoft continued developing their respective products. In 1996, Sybase changed the name of its product to Adaptive Server Enterprise (ASE) as a means to differentiate its SQL Server product from Microsoft SQL Server. In the late 1990's Sybase started to lose its battle against Oracle and Microsoft SQL server due to its buggy release, overly aggressive sales strategies, pessimistic partners, merger complications and management turnover. The latest ASE version is SAP ASE 16.0.
Naïve (Page-Level) Naïve (Record-Level)
ASE provides row-level and page-level compression. Row-level compression is for fixed-length regular data. Some fixed-length data types, such as tiny integer (which uses 1 byte), cannot be compressed. Page-level compression compresses redundant data on a page. A compressed ASE database can include both compressed and uncompressed tables or partitions.
ASE uses a cost-based query optimizer. The optimizer relies on information about tables, indexes, partitions, and columns referenced by a query to estimate the cost in terms of I/O and CPU time for possible query plans, and then chooses the lowest estimated cost plan. The optimizer is efficient for both OLTP and OLAP workloads. Optimization strategies can be selected based on need.
ASE uses the Virtual Server Architecture to take advantage of the parallel processing done by symmetric multiprocessing systems. ASE can be run as a single process, a single multi-threaded process, or multiple cooperating processes. The ASE Cluster Edition 16sp01 supports RDMA.
ASE uses B tree indexing, and indexes provided are clustered or non-clustered. Only one clustered index can be created on a table, but up to 249 non-clustered indexes can be created per table. Index entries are stored as rows on index pages and contain key and value pointers to lower levels of the index, data pages, or individual data rows. An index on a 15-byte field has around 100 rows per index page. If a table is partitioned, local and global indexes can be created.
Multi-version Concurrency Control (MVCC) Two-Phase Locking (Deadlock Prevention) Two-Phase Locking (Deadlock Detection)
Sybase ASE provides multi-version concurrency control (using in-memory row versioning or on-disk MVCC), which enables concurrent read-writes where rows can be locked for writing in one session while read access is granted to unchanged rows in a different session. ASE supports locking at table, page, and row level by providing allpages locking, datapages locking, and datarows locking.
For each scheme, ASE can acquire a table lock for the entire table or can acquire page and row locks to lock only certain pages or rows. The types of page and row locks include shared locks for read operations, exclusive locks for inserts, deletes, and updates, and update locks during the initial phases of an update, delete, or fetch.
Logical Logging Physical Logging
Transactions are used to track database changes. A transaction consists of one or many Transact-SQL statements that all succeed or fail. Each database has a transaction log, which is a write-ahead log, so changes are logged before the change is made to a disk page. If any statement in a transaction fails, all changes made by the transaction are rolled back.
Intra-Operator (Horizontal) Inter-Operator (Vertical)
ASE supports parallel execution of one query with multiple workers.
ASE supports stored procedures written using SQL. ASE also supports extended stored procedures. Extended stored procedures have the interface of a stored procedure but do not contain SQL statements and instead execute procedural language code that has been compiled into a dynamic link library. The procedural language can be written in any language that can call C functions and manipulate C datatypes.
Read Uncommitted Read Committed Serializable Repeatable Read
ASE provides four isolation levels (higher levels include restrictions of lower levels):
Nested Loop Join Hash Join Sort-Merge Join
Sybase ASE provides four main joins: NESTED LOOP JOIN
, MERGE JOIN
, HASH JOIN
, and NARY NESTED LOOP JOIN
(a variant of nested loop join). Nested loop join works well with relatively small data sets, merge join works well for moderately sized data sets, and hash join performs well for large datasets. Hash joins parallelize and scale better than other joins and maximize throughput well in data warehouses.
Traditional ASE databases are disk-oriented. ASE 15.5 supports in-memory databases such that the database runs entirely in the Adaptive Server memory space (cache), so neither log nor data is ever written to disk, and I/O is not required. Its performance can be better than a disk-oriented database, at the cost of durability. In the event of memory failure, the database cannot be recovered.
ASE provides logical constructs (devices) for mapping of the operating system data files. A database is built on devices and can span multiple devices. One device can only be associated with one data file or raw partition. When a database is created on devices or a device fragment, three segments (system, default, and log) are generated automatically on each corresponding device or device fragment.
https://www.sap.com/products/sybase-ase.html
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1987
Sybase SQL Server
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