Graefe, Goetz, “Encapsulation of Parallelism in the Volcano Query Processing System ; CU-CS” (). Computer Science Technical Reports. Encapsulation of parallelism in the volcano query processing system – Graefe ‘ You may have picked up on the throwaway line in the Impala. Encapsulation of Parallelism in the Volcano Query Processing System (). The Volcano query processing system uses the operator model of query.

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Encapsulation of Parallelism in the Volcano Query Processing System – Semantic Scholar

When attempting to parallelize Volcano, we had to choose between two models of parallelization, called here the bracket and operator models. Run-time adaptation in river Remzi H.

The module responsible for parallel execution and synchronization peocessing the exchange iterator. By clicking accept or continuing to use the site, you agree to the terms outlined in our Privacy PolicyTerms of Serviceand Dataset License. The next operation requests records from its input tree, possibly sending them off to other processes in the group, until a record for its own partition is found.

The exchange operator in the consumer process acts as a normal iterator, the only difference from other iterators is that it receives its input via inter-process communication. Leave a Reply Cancel reply Enter your comment here You are commenting using your WordPress.

Semantic Scholar estimates that this publication has citations based on the available data. Bushy parallelism can easily be implemented by inserting one or two exchange operators into a query tree. It includes an exchange operator that allows intra-operator parallelism on partitioned datasets and both vertical and horizontal inter-operator parallelism.

For example, in order to sort two inputs into a merge-join in parallel, the first or both inputs are separated from the merge-join by an exchange operation.


In Volcano, queries are expressed as complex algebra expressions, and the operators are query processing algorithms. A variation on this theme was implemented as part of a parallel sort algorithm: Parallel computing Dataflow Parallel database. Given this, the way that Volcano introduces parallelism is very simple: This scheme has been used very effectively for broadcast communication and synchronization in binary hypercubes.

Thus, the two sort operations are working in parallel. You are commenting using your Facebook account. The parent process turns to the second sort immediately after forking the child process that will produce the first input in sorted order. Citation Statistics Citations 0 10 20 30 ’90 ’96 ’03 ’10 ‘ The iterators support a simple open-next-close protocol. Post was not sent – check your email addresses!

A process runs a producer and produces input for the other processes only if it does not have input for the consumer. This mode of operation also makes flow control obsolete. This site uses Akismet to reduce spam. Fill in your details below or click an icon to log in: This paper has highly influenced 21 other papers.

Email required Address never made public. Enterprise Database Applications and the Cloud: ShahJoseph M. We call this concept anonymous inputs or streams … Streams represent the most efficient execution model in terms of time overhead for sychronizing operators and space number of records that must reside in memory concurrently for single process query evaluation.

Encapsulation of Parallelism in the Volcano Query Processing System

See our FAQ for additional information. You are commenting using your Twitter account. Querg we changed our initial implementation from forking all producer processes by the master to using a propagation tree scheme, we observed significant performance improvements.


HellersteinEric A.

All operators are designed and coded as if they were meant for a single-process system only. In such a scheme, the master forks one slave, then both fork a new slave each, then all four fork a new slave each, etc. You may have picked up on the throwaway line in the Impala paper: Subscribe never miss an issue!

Twitter LinkedIn Encapuslation Print. Citations Publications citing this paper. Whereas normal operators use a demand-driven dataflow iterators calling nextexchanges use data-driven dataflows eager evaluation. This paper has citations.

Notify me of new comments via email. The Morning Paper delivered straight to your inbox. A propagation tree then forks the other processes needed one per partition:. sysgem

Encapsulation networking Systems theory Process architecture. The key benefit of the exchange operator technique is that is allows query processing algorithms to be coded for single-process execution but run in a highly parallel environment without modifications. For pipelined parallelism, the open procedure of the exchange operator forks a processnig process, with the parent process acting parllelism the consumer, and the child process as the producer. This removes some communication overhead.

The uniform interface between operators makes Volcano extensible by new operators. The exchange operator can be used to implement pipelined parallelism called vertical parallelism in the paperbushy parallelism processing different subtrees of a complex query tree in paralleland intra-operator parallelism partitioning the dataset and thhe partitions in parallel for a single operator. Learn how your comment data is processed.