Snowflake Inc.

Alexander Miller

William H Waddington

Chen Luo

Zhaohui Zhang

Thierry Cruanes

Cristian Diaconu

Max Heimel

Moritz Eyssen

Lishi Jiang

Khaled Yagoub

Leonidas Galanis

Dimitrios Tsirogiannis

Nikolaos Romanos Katsipoulakis

Mingze Xu

The subject technology receives a key-value pair. The subject technology determines a value size of the key-value pair is greater than a threshold size for an out of line blob (OLB) key space. The subject technology performs a write operation of a key-pointer pair into a regular space. The subject technology performs a plurality of write operations for multiple key-value parts of the key-value pair into the OLB key space. The subject technology performs conflict checking of the regular space for the key-value pair.

Optimizations to read and write transactions for large values in distributed databases

The subject technology initializes a statement for execution. The subject technology determines that the statement has been executing for longer than a minimum statement timeout. The subject technology periodically updates a read timestamp table with a new update timestamp for an entry corresponding to the statement. The subject technology determines whether the entry corresponding to the statement has been removed from the read timestamp table. The subject technology, in response to determining that the entry has not been removed from the read timestamp table, removes the entry from the read timestamp table. The subject technology provides a set of results from completing execution of the statement.

Automated tracking of oldest running statement in distributed MVCC databases

The subject technology receives, at a first execution node, a first transaction, the first transaction to be executed on linearizable storage. The subject technology determines whether the first execution node corresponds to a rank indicating a leader worker. The subject technology, in response to the first execution node corresponding to the rank indicating the leader worker, performs, by the first execution node, an initialization process for executing the first transaction. The subject technology broadcasts a first read timestamp associated with the first transaction to a set of execution nodes, the set of execution nodes being different than the first execution node. The subject technology executes, by the first execution node, at least a first operation from the first transaction.

Distributed execution of transactional queries

The subject technology performs, using asynchronous threads of execution nodes of a distributed database, asynchronous transformation and compaction of key-value pairs of data that correspond to a plurality of transactional queries, the asynchronous threads transforming the key-value pairs from an initial format to a commit format that includes a commit time of data committed to the distributed database, the asynchronous threads compacting the key-value pairs by deleting the key-value pairs in the initial format. The subject technology processes, using transactional threads in the execution nodes, the plurality of transactional queries to generate results data, the asynchronous threads performing the asynchronous transformation and compaction while the transactional threads generate the results data. The subject technology stores the results data.

Scalable compaction for a distributed database

The subject technology receives a statement to initiate an online index building process of an index. The subject technology determines that the index can be generated. The subject technology performs a write operation to store an index record indicating an initial status of the online index building process. The subject technology performs a statement fencing process. The subject technology performs a back-filling process of the index. The subject technology validates the index.

Online index creation for multi-version database without table locks

The subject technology determines that a first visible version of a key is not one of a N number of newest versions of the key based on searching for the key in a regular space to locate the first visible version of the key. The subject technology performs a search of an undo space to locate a second visible version of the key. The subject technology determines whether the first visible version or the second visible version of the key is newer. The subject technology provides a newer version of the key between the first visible version and the second visible version of the key.

Long-lived statements optimizations in a database system

The subject technology inserts, by a first transaction, a new version of an object, the first transaction including a first statement to perform an update operation to a row in a first table, the object corresponding to data in the row to be updated, the first statement including information comprising an object key associated with the object. The subject technology performs, by a second transaction, a range read, the range read including information indicating the object key. The subject technology receives a set of conflicting transactions from the range read. The subject technology determines that a conflict occurred between the first transaction and a third transaction from the set of conflicting transactions. The subject technology performs a restart of the first transaction in response to determining that the conflict occurred.

Concurrency control for transactions in database systems

The subject technology performs a locking operation on a first set of keys by a first statement of a first transaction. The subject technology determines that a conflict occurred between the first statement and a second transaction. The subject technology determines that the second transaction has yet to complete after a predetermined period of time. The subject technology performs a deadlock detection process where the subject technology stores a key and value in a table indicating the first transaction and the second transaction, detects, based at least in part on a graph traversal of the table starting from the first transaction, a cycle between the first transaction and the second transaction, and determines that the first transaction is a youngest transaction in the detected cycle. The subject technology ceases execution of the first transaction in response to the first transaction being a youngest transaction in a detected cycle.

Deadlock detection in distributed databases

The subject technology receives a first transaction, the first transaction to be executed on linearizable storage. The subject technology assigns, prior to performing a read operation, a first read version to the first transaction, the first read version indicating a first version of the linearizable storage, the first read version corresponding to a particular timestamp of a current time. The subject technology performs the read operation from the first transaction on a table in a database. The subject technology determines a first commit version identifier corresponding to first data resulting from the read operation. The subject technology proceeds to perform a particular write operation from the first transaction. The subject technology determines that the first commit version identifier fails to match a second commit version identifier corresponding to a second transaction. The subject technology aborts the particular write operation from the first transaction.

Managing concurrent transactions in database systems

A distributed database compaction system can perform compaction for transactional queries in an asynchronous matter without affecting completion of the queries. The compaction system can implement asynchronous transformation of key pairs in the database, and older keys can be periodically purged using a scheduled compactor. Subsequent queries use the compacted stored keys to perform efficient queries with direct reads of committed transactions and more efficient access to key values stores of the distributed database.

Scalable compaction in a concurrent transaction processing distributed database

The subject technology performs a search for a key in a regular space to locate a first visible version of the key. The subject technology determines that the first visible version of the key is not one of a N number of newest versions of the key. The subject technology performs a search of an undo space to locate a second visible version of the key. The subject technology determines whether the first visible version or the second visible version of the key is newer. The subject technology provides a newer version of the key between the first visible version and the second visible version of the key.

Optimizations for long-lived statements in a database system

A hybrid network-based database system for handling OLTP and OLAP queries using decoupled compute and storage devices. A set of decoupled compute instances perform transactions on an OLTP database, and the data is replicated to an OLAP database, which is managed by another set of decoupled compute instances. Further, in response to queries, the database system can retrieve data from the OLTP and OLAP database for merging and processing according to the query.

Aggregate and transactional networked database query processing

The subject technology receives a first transaction. The subject technology assigns a first read version to the first transaction, the first read version indicating a first version of the linearizable storage. The subject technology performs a read operation from the first transaction on a table in a database. The subject technology determines a first commit version identifier corresponding to first data resulting from the read operation. The subject technology, in response to determining that a particular write operation is absent from the first transaction, proceeding to execute a different transaction and foregoing to perform a commit process in connection with the first transaction.

Concurrent transaction processing in a database system

The subject technology inserts, by a first transaction, a new version of an object, the inserting corresponding to a first statement from the first transaction, the first statement including information indicating a first key, a first transaction identifier, a first statement number, and a first restart count. The subject technology performs, by a second transaction, a range read, the range read including information indicating the first key. The subject technology receives, after performing the range read, a set of conflicting transactions. The subject technology determines that a conflict occurred between the first transaction and a third transaction from the set of conflicting transactions.

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San Mateo, CA, United States of America

Alexander Miller