SQL/MX Queuing and Publish/Subscribe Services

Introduction
HP NonStop SQL/MX Queuing and Publish/Subscribe Services—523734-002
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Terminology
and update a row in a single call. Again, the application code is simpler and
performs better. Figure 1-2 shows the processing required.
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Publish/subscribe can use a special access mode, skip conflict access. As a result,
the various instances of the invoice processing application skip rows that are
locked and select and update other available rows. The application achieves better
performance without having to use a partitioning scheme.
Terminology
These terms are specific to publish/subscribe:
Figure 1-2. Invoice Processing With Publish/Subscribe
Publishing Inserting or updating rows of data in a queue or channel by using an
INSERT or UPDATE statement.
Subscribing Subscribing to entries in a queue or channel by using a SELECT
statement specifying stream access to be notified when changes
occur.
Stream
access
Changes the behavior of a table in a SELECT or embedded
UPDATE or DELETE statement. When no more rows satisfy the
selection predicate, the statement waits for more rows.
Queue A database table read and updated in stream access mode, using an
UPDATE or DELETE statement embedded in the FROM clause of a
SELECT statement. Only a single subscriber will receive the new
entry.
Channel A database table used by applications specifying stream access to
subscribe to newly published entries. The entries remain in the table.
All subscribers receive new entries.
Open cursor
Embedded
UPDATE
from stream
of invoices
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