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new c9e7d88 GEODE-5287 Incorporate ACID semantics into transaction intro
docs (#2032)
c9e7d88 is described below
commit c9e7d8879d30926e5cbbfc71e54b6a75055357c6
Author: Karen Miller <[email protected]>
AuthorDate: Wed Jun 6 13:32:31 2018 -0700
GEODE-5287 Incorporate ACID semantics into transaction intro docs (#2032)
* GEODE-5287 Incorporate ACID semantics into transaction intro docs
* GEODE-5287 Implemented review suggestion and fixed a broken link
---
.../source/subnavs/geode-subnav.erb | 5 +--
.../transactions/about_transactions.html.md.erb | 37 ++++++++++++++-
.../transactions/chapter_overview.html.md.erb | 4 +-
.../how_cache_transactions_work.html.md.erb | 2 -
.../transactions/transaction_semantics.html.md.erb | 52 ----------------------
5 files changed, 39 insertions(+), 61 deletions(-)
diff --git a/geode-book/master_middleman/source/subnavs/geode-subnav.erb
b/geode-book/master_middleman/source/subnavs/geode-subnav.erb
index c2c3cff..a37cbf6 100644
--- a/geode-book/master_middleman/source/subnavs/geode-subnav.erb
+++ b/geode-book/master_middleman/source/subnavs/geode-subnav.erb
@@ -1372,7 +1372,7 @@ limitations under the License.
<a
href="/docs/guide/<%=vars.product_version_nodot%>/developing/transactions/chapter_overview.html">Transactions</a>
<ul>
<li>
- <a
href="/docs/guide/<%=vars.product_version_nodot%>/developing/transactions/about_transactions.html">About
Transactions</a>
+ <a
href="/docs/guide/<%=vars.product_version_nodot%>/developing/transactions/about_transactions.html">Introduction
and the Application of ACID Semantics</a>
</li>
<li class="has_submenu">
<a
href="/docs/guide/<%=vars.product_version_nodot%>/developing/transactions/cache_transactions.html">Geode
Cache Transactions</a>
@@ -1481,9 +1481,6 @@ limitations under the License.
</li>
</ul>
</li>
- <li>
- <a
href="/docs/guide/<%=vars.product_version_nodot%>/developing/transactions/transaction_semantics.html">Geode
Cache Transaction Semantics</a>
- </li>
</ul>
</li>
</ul>
diff --git a/geode-docs/developing/transactions/about_transactions.html.md.erb
b/geode-docs/developing/transactions/about_transactions.html.md.erb
index bc9e371..a0a9047 100644
--- a/geode-docs/developing/transactions/about_transactions.html.md.erb
+++ b/geode-docs/developing/transactions/about_transactions.html.md.erb
@@ -1,5 +1,5 @@
---
-title: About Transactions
+title: Introduction and the Application of ACID Semantics
---
<!--
@@ -45,3 +45,38 @@ JTA global transactions allow you to use the standard JTA
interface to coordinat
You can also coordinate a <%=vars.product_name%> cache transaction with an
external database by specifying database operations within cache and
transaction application plug-ins (CacheWriters/CacheListeners and
TransactionWriters/TransactionListeners.) This is an alternative to using JTA
transactions. See [How to Run a <%=vars.product_name%> Cache Transaction that
Coordinates with an External
Database](run_a_cache_transaction_with_external_db.html#task_sdn_2qk_2l).
+## Application of ACID Semantics
+
+<%=vars.product_name%> transaction semantics differ in some ways from the
Atomicity-Consistency-Isolation-Durability (ACID) semantics of traditional
relational databases. For performance reasons, <%=vars.product_name%>
transactions do not adhere to ACID constraints by default, but can be
configured for ACID support as described in this section.
+
+### <a id="transaction_semantics__section_8362ACD06C784B5BBB0B7E986F760169"
class="no-quick-link"></a>Atomicity
+
+Atomicity is “all or nothing” behavior: a transaction completes successfully
only when all of the operations it contains complete successfully. If problems
occur during a transaction, perhaps due to other transactions with overlapping
changes, the transaction cannot successfully complete until the problems are
resolved.
+
+<%=vars.product_name%> transactions provide atomicity and realize speed by
using a reservation system, instead of using the traditional relational
database technique of a two-phase locking of rows. The reservation prevents
other, intersecting transactions from completing, allowing the commit to check
for conflicts and to reserve resources in an all-or-nothing fashion prior to
making changes to the data. After all changes have been made, locally and
remotely, the reservation is released. [...]
+
+### <a id="transaction_semantics__section_7C287DA4A5134780B3199CE074E3F890"
class="no-quick-link"></a>Consistency
+
+Consistency requires that data written within a transaction must observe the
key and value constraints established for the affected region. Note that
validity of the transaction is the responsibility of the application.
+
+### <a id="transaction_semantics__section_126A24EC499D4CF39AE766A0B526A9A5"
class="no-quick-link"></a>Isolation
+
+Isolation assures that operations will see either the pre-transaction state of
the system or its post-transaction state, but not the transitional state that
occurs while a transaction is in progress. Write operations in a transaction
are always confirmed to ensure that stale values are not written. As a
distributed cache-based system optimized for performance,
<%=vars.product_name%> in its default configuration does not enforce read
isolation. <%=vars.product_name%> transactions support [...]
+
+In the default configuration, <%=vars.product_name%> isolates transactions at
the process thread level, so while a transaction is in progress, its changes
are visible only inside the thread that is running the transaction. Threads
inside the same process and in other processes cannot see changes until after
the commit operation begins. At this point, the changes are visible in the
cache, but other threads that access the changing data might see only partial
results of the transaction lea [...]
+
+If an application requires the slower conventional isolation model (such that
dirty reads of transitional states are not allowed), read operations must be
encapsulated within transactions and the `gemfire.detectReadConflicts`
parameter must be set to ‘true’:
+
+`-Dgemfire.detectReadConflicts=true`
+
+This parameter causes read operations to succeed only when they read a
consistent pre- or post-transactional state. If not, a
`CommitConflictException` is thrown to the calling application.
+
+### <a id="transaction_semantics__section_F092E368724945BCBF8E5DCB36B97EB4"
class="no-quick-link"></a>Durability
+
+Relational databases provide durability by using disk storage for recovery and
transaction logging. As a distributed cache-based system optimized for
performance, <%=vars.product_name%> does not support on-disk or in-memory
durability for transactions.
+
+Applications can emulate the conventional disk-based durability model by
setting the `gemfire.ALLOW_PERSISTENT_TRANSACTIONS` parameter to ‘true’.
+
+`-Dgemfire.ALLOW_PERSISTENT_TRANSACTIONS=true`
+
+This allows permanent regions to participate in transactions, thus providing
disk-based durability. See [Transactions and Persistent
Regions](cache_transactions_by_region_type.html#concept_omy_341_wk) for more
detail on the use of this parameter.
diff --git a/geode-docs/developing/transactions/chapter_overview.html.md.erb
b/geode-docs/developing/transactions/chapter_overview.html.md.erb
index 0f2dc37..ae85405 100644
--- a/geode-docs/developing/transactions/chapter_overview.html.md.erb
+++ b/geode-docs/developing/transactions/chapter_overview.html.md.erb
@@ -21,9 +21,9 @@ limitations under the License.
<%=vars.product_name%> provides a transactions API, with `begin`, `commit`,
and `rollback` methods. These methods are much the same as the familiar
relational database transactions methods.
-- **[About Transactions](about_transactions.html)**
+- **[Introduction and the Application of ACID
Semantics](about_transactions.html)**
- This section covers the features of <%=vars.product_name%> transactions.
+ This section presents the features of <%=vars.product_name%> transactions
and discusses how the implementation adheres to ACID semantics.
It also details the two kinds of transaction that <%=vars.product_name%>
supports:
**<%=vars.product_name%> cache transactions** and **JTA global transactions**.
diff --git
a/geode-docs/developing/transactions/how_cache_transactions_work.html.md.erb
b/geode-docs/developing/transactions/how_cache_transactions_work.html.md.erb
index c7bca5b..a72cce7 100644
--- a/geode-docs/developing/transactions/how_cache_transactions_work.html.md.erb
+++ b/geode-docs/developing/transactions/how_cache_transactions_work.html.md.erb
@@ -33,8 +33,6 @@ All the regions in a <%=vars.product_name%> member cache can
participate in a tr
- **[Comparing Transactional and Non-Transactional
Operations](transactional_and_nontransactional_ops.html#transactional_and_nontransactional_ops)**
-- **[<%=vars.product_name%> Cache Transaction
Semantics](transaction_semantics.html)**
-
## Transaction View
A transaction is isolated from changes made concurrently to the cache. Each
transaction has its own private view of the cache, including the entries it has
read and the changes it has made. The first time the transaction touches an
entry in the cache, either to read or write, it produces a snapshot of that
entry’s state in the transaction’s view. The transaction maintains its current
view of the entry, which reflects only the changes made within the transaction.
The transaction remembers [...]
diff --git
a/geode-docs/developing/transactions/transaction_semantics.html.md.erb
b/geode-docs/developing/transactions/transaction_semantics.html.md.erb
deleted file mode 100644
index 3df3f20..0000000
--- a/geode-docs/developing/transactions/transaction_semantics.html.md.erb
+++ /dev/null
@@ -1,52 +0,0 @@
-<% set_title(product_name, "Cache Transaction Semantics") %>
-
-<!--
-Licensed to the Apache Software Foundation (ASF) under one or more
-contributor license agreements. See the NOTICE file distributed with
-this work for additional information regarding copyright ownership.
-The ASF licenses this file to You under the Apache License, Version 2.0
-(the "License"); you may not use this file except in compliance with
-the License. You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
--->
-
-<%=vars.product_name%> transaction semantics differ in some ways from the
Atomicity-Consistency-Isolation-Durability (ACID) semantics of traditional
relational databases. For performance reasons, <%=vars.product_name%>
transactions do not adhere to ACID constraints by default, but can be
configured for ACID support as described in this section.
-
-## <a id="transaction_semantics__section_8362ACD06C784B5BBB0B7E986F760169"
class="no-quick-link"></a>Atomicity
-
-Atomicity is “all or nothing” behavior: a transaction completes successfully
only when all of the operations it contains complete successfully. If problems
occur during a transaction, perhaps due to other transactions with overlapping
changes, the transaction cannot successfully complete until the problems are
resolved.
-
-<%=vars.product_name%> transactions provide atomicity and realize speed by
using a reservation system, instead of using the traditional relational
database technique of a two-phase locking of rows. The reservation prevents
other, intersecting transactions from completing, allowing the commit to check
for conflicts and to reserve resources in an all-or-nothing fashion prior to
making changes to the data. After all changes have been made, locally and
remotely, the reservation is released. [...]
-
-## <a id="transaction_semantics__section_7C287DA4A5134780B3199CE074E3F890"
class="no-quick-link"></a>Consistency
-
-Consistency requires that data written within a transaction must observe the
key and value constraints established for the affected region. Note that
validity of the transaction is the responsibility of the application.
-
-## <a id="transaction_semantics__section_126A24EC499D4CF39AE766A0B526A9A5"
class="no-quick-link"></a>Isolation
-
-Isolation assures that operations will see either the pre-transaction state of
the system or its post-transaction state, but not the transitional state that
occurs while a transaction is in progress. Write operations in a transaction
are always confirmed to ensure that stale values are not written. As a
distributed cache-based system optimized for performance,
<%=vars.product_name%> in its default configuration does not enforce read
isolation. <%=vars.product_name%> transactions support [...]
-
-In the default configuration, <%=vars.product_name%> isolates transactions at
the process thread level, so while a transaction is in progress, its changes
are visible only inside the thread that is running the transaction. Threads
inside the same process and in other processes cannot see changes until after
the commit operation begins. At this point, the changes are visible in the
cache, but other threads that access the changing data might see only partial
results of the transaction lea [...]
-
-If an application requires the slower conventional isolation model (such that
dirty reads of transitional states are not allowed), read operations must be
encapsulated within transactions and the `gemfire.detectReadConflicts`
parameter must be set to ‘true’:
-
-`-Dgemfire.detectReadConflicts=true`
-
-This parameter causes read operations to succeed only when they read a
consistent pre- or post-transactional state. If not, a
`CommitConflictException` is thrown to the calling application.
-
-## <a id="transaction_semantics__section_F092E368724945BCBF8E5DCB36B97EB4"
class="no-quick-link"></a>Durability
-
-Relational databases provide durability by using disk storage for recovery and
transaction logging. As a distributed cache-based system optimized for
performance, <%=vars.product_name%> does not support on-disk or in-memory
durability for transactions.
-
-Applications can emulate the conventional disk-based durability model by
setting the `gemfire.ALLOW_PERSISTENT_TRANSACTIONS` parameter to ‘true’.
-
-`-Dgemfire.ALLOW_PERSISTENT_TRANSACTIONS=true`
-
-This allows permanent regions to participate in transactions, thus providing
disk-based durability. See [Transactions and Persistent
Regions](cache_transactions_by_region_type.html#concept_omy_341_wk) for more
detail on the use of this parameter.
--
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