Database system with database engine and separate distributed storage service

摘要

A database system may include a database service and a separate distributed storage service. The database service (or a database engine head node thereof) may be responsible for query parsing, optimization, and execution, transactionality, and consistency, while the storage service may be responsible for generating data pages from redo log records and for durability of those data pages. For example, in response to a write request directed to a particular data page, the database engine head node may generate a redo log record and send it, but not the data page, to a storage service node. The storage service node may store the redo log record and return a write acknowledgement to the database service prior to applying the redo log record. The server node may apply the redo log record and other redo log records to a previously stored version of the data page to create a current version.

主权项

1. A computing system, comprising:
a plurality of computing nodes, each of which comprises at least one processor and a memory; wherein one or more of the plurality of computing nodes is configured to implement a database service, and wherein the database service comprises a database engine head node; wherein two or more other ones of the plurality of computing nodes are configured to implement server nodes of a distributed storage service that stores portions of database tables as respective data pages on one or more storage devices; wherein the database engine head node is configured to:
receive, from a client of the database service, a write request directed to a given data record in a database table, wherein the write request specifies a modification to be made to the given data record;generate a redo log record representing the modification to be made to the given data record;send the redo log record, but not a data page comprising the given data record, to a particular server node of the distributed storage service that stores a version of the data page comprising the given data record; wherein the particular server node of the distributed storage service is configured to:
receive the redo log record from the database engine head node;write the redo log record to one or more storage devices;return, to the database engine head node, an acknowledgement that the redo log record was written; andsubsequent to returning the acknowledgement:
generate a current version of the data page comprising the given data record, wherein to generate the current version of the data page, the particular server node of the distributed storage service is configured to apply the received redo log record and one or more other redo log records representing modifications to the data page to a previously stored version of the data page; andwrite the current version of the data page to one or more storage devices.