Amit Ganesh

Fast-Start: quick fault recovery in oracle

Availability requirements for database systems are more stringent than ever before with the widespread use of databases as the foundation for ebusiness. This paper highlights Fast-Start#8482; Fault Recovery, an important availability feature in Oracle, designed to expedite recovery from unplanned outages. Fast-Start allows the administrator to configure a running system to impose predictable bounds on the time required for crash recovery. For instance, fast-start allows fine-grained control over the duration of the roll-forward phase of crash recovery by adaptively varying the rate of checkpointing with minimal impact on online performance. Persistent transaction locking in Oracle allows normal online processing to be resumed while the rollback phase of recovery is still in progress, and fast-start allows quick and transparent rollback of changes made by uncommitted transactions prior to a crash.

Oracle Database In-Memory: A dual format in-memory database

The Oracle Database In-Memory Option allows Oracle to function as the industry-first dual-format in-memory database. Row formats are ideal for OLTP workloads which typically use indexes to limit their data access to a small set of rows, while column formats are better suited for Analytic operations which typically examine a small number of columns from a large number of rows. Since no single data format is ideal for all types of workloads, our approach was to allow data to be simultaneously maintained in both formats with strict transactional consistency between them.

Oracle database filesystem

Modern enterprise, web, and multimedia applications are generating unstructured content at unforeseen volumes in the form of documents, texts, and media files. Such content is generally associated with relational data such as user names, location tags, and timestamps. Storage of unstructured content in a relational database would guarantee the same robustness, transactional consistency, data integrity, data recoverability and other data management features consolidated across files and relational contents. Although database systems are preferred for relational data management, poor performance of unstructured data storage, limited data transformation functionalities, and lack of interfaces based on filesystem standards may keep more than eighty five percent of non-relational unstructured content out of databases in the coming decades. We introduce Oracle Database Filesystem (DBFS) as a consolidated solution that unifies state-of-the-art network filesystem features with relational database management ones. DBFS is a novel shared-storage network filesystem developed in the RDBMS kernel that allows content management applications to transparently store and organize files using standard filesystem interfaces, in the same database that stores associated relational content. The server component of DBFS is based on Oracle SecureFiles, a novel unstructured data storage engine within the RDBMS that provides filesystem like or better storage performance for files within the database while fully leveraging relational data management features such as transaction atomicity, isolation, read consistency, temporality, and information lifecycle management. We present a preliminary performance evaluation of DBFS that demonstrates more than 10TB/hr throughput of filesystem read and write operations consistently over a period of 12 hours on an Oracle Exadata Database cluster of four server nodes. In terms of file storage, such extreme performance is equivalent to ingestion of more than 2500 million 100KB document files a single day. The set of initial results look very promising for DBFS towards becoming the universal storage solution for both relational and unstructured content.

Oracle SecureFiles System

Over the last decade, the nature of content stored on computer storage systems has evolved from being relational to being semi-structured, i.e., unstructured data accompanied by relational metadata. Average data volumes have increased from a few hundred megabytes to hundreds of terabytes. Simultaneously, data feed rates have also increased with increase in processor, storage and network bandwidths. Data growth trends seem to be following Moores law and thereby imply an exponential explosion in content volumes and rates in the years to come. The near future poses requirements for data management systems to provide solutions that provide unlimited scalability in execution, availability, recoverability and storage usage of semi-structured content. Traditionally, filesystems have been preferred over database management systems for providing storage solutions for unstructured data, while databases have been the preferred choice to manage relational data. Lack of consolidated semi-structured content management architecture compromises security, availability, recoverability, and manageability among other features. We introduce a system without compromises, the Oracle SecureFiles System, designed to provide highly scalable storage and access execution of unstructured and structured content as first-class objects within the Oracle relational database management system. Oracle SecureFiles breaks the performance barrier that has kept such content out of databases. The architecture provides capability to maximize utilization of storage usage through compression and de-duplication and achieves robustness by preserving transactional atomicity, durability, availability, read-consistent query-ability and security of the database management system.

Logging last resource optimization for distributed transactions in Oracle WebLogic server

State-of-the-art OLTP systems execute distributed transactions using XA-2PC protocol, a presumed-abort variant of the Two-Phase Commit (2PC) protocol. While the XA specification provides for the Read-Only and 1PC optimizations of 2PC, it does not deal with another important optimization, coined Nested 2PC. In this paper, we describe the Logging Last Resource (LLR) optimization in Oracle WebLogic Server (WLS). It adapts and improves the Nested 2PC optimization to/for the Java Enterprise Edition (JEE) environment. It allows reducing the number of forced (synchronous) writes and the number of exchanged messages when executing distributed transactions that span multiple transactional resources including a SQL database integrated as a JDBC datasource. This optimization has been validated in SPECjAppServer2004 (a standard industry benchmark for JEE) and a variety of internal benchmarks. LLR has been successfully deployed by high-profile customers in mission-critical high-performance applications.

Oracle SecureFiles: prepared for the digital deluge

Digital unstructured data volumes across enterprise, Internet and multimedia applications are predicted to surpass 6.023x1023 (Avogadros number) bits a year in the next fifteen years. This poses tremendous scalability challenges for data management solutions in the coming decades. Filesystems seem to be preferred by data management application designers for providing storage solutions for such unstructured data volumes. Oracle SecureFiles is emerging as the database solution to break the performance barrier that has kept unstructured content out of database management systems and to provide advanced filesystem functionality, while letting applications fully leverage the strengths of the RDBMS from transactions to partitioning to rollforward recovery. A set of preliminary performance results was presented at the 34th International Conference on Very Large Data Bases (VLDB 2008). It was claimed that SecureFiles would scale maximally as physical storage systems scale up. We legitimize our claims on SecureFiles scalability through this paper, presenting the scalability aspects of SecureFiles through a performance evaluation of I/O bound filesystem like operations on one of the latest high performance cluster of servers and storage. We are presenting benchmark results that we believe represent a world record database insertion rate for any published result - at over 4.4GB/S using a cluster of seven servers. For 100 byte rows, that represents an insertion rate of 45 billion records a second in relational terms. In terms of unstructured data storage, the scale represents an insertion rate of more than 3.7 million 100 MB high-resolution multimedia videos a day.