Can the transaction log history size scale?


No, this isn't a likely problem for Bitcoin. Or, to be more specific, it is a problem that there known ways to solve.

First of all, there is a concept called a selfish client. Which means a client that can create and receive transactions, but doesn't maintain the blockchain. It's considered "selfish" because it isn't performing the work expected of a true node on the system: it only maintains the information needed for it's own transactions. These types of clients are already common in the mobile world today, where 8GB is already too much to handle.

But if we got to a scenario where the blockchain was too unwieldy for the typical client, we would also probably be in a scenario where the network already had a sufficient number of server nodes to handle the "network".

Second, Bitcoin already has the concept of discarding transactions once they are spent. (It is made possible by the way that transactions are stored in the block: via the Merkle tree.) It is...

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Every SQL Server database has a transaction log that records all transactions and the database modifications made by each transaction.

The transaction log is a critical component of the database. If there is a system failure, you will need that log to bring your database back to a consistent state. Never delete or move this log unless you fully understand the ramifications of doing so.

Fun fact! Known good points from which to begin applying transaction logs during database recovery are created by checkpoints. For more information, see Database Checkpoints (SQL Server).

Operations supported by the transaction log

The transaction log supports the following operations:

Individual transaction recovery.

Recovery of all incomplete transactions when SQL Server is started.

Rolling a restored database, file, filegroup, or page forward to the point of failure.

Supporting transactional replication.

Supporting high...

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In the field of databases in computer science, a transaction log (also transaction journal, database log, binary log or audit trail) is a history of actions executed by a database management system used to guarantee ACID properties over crashes or hardware failures. Physically, a log is a file listing changes to the database, stored in a stable storage format.

If, after a start, the database is found in an inconsistent state or not been shut down properly, the database management system reviews the database logs for uncommitted transactions and rolls back the changes made by these transactions. Additionally, all transactions that are already committed but whose changes were not yet materialized in the database are re-applied. Both are done to ensure atomicity and durability of transactions.

This term is not to be confused with other, human-readable logs that a database management system usually provides.

In database management systems, a journal is the record...

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Shrinking the transaction log reduces its physical size by removing one or more inactive virtual log files. The unit of the size reduction is always the virtual log file. For example, if you have a 600 megabyte (MB) log file that has been divided into six 100 MB virtual logs, the size of the log file can only be reduced in 100 MB increments. The file size can be reduced to sizes such as 500 MB or 400 MB, but the file cannot be reduced to sizes such as 433 MB or 525 MB. A virtual log file that holds any active log records, that is, an active virtual log file, is part of the logical log, and it cannot be removed. For more information, see Transaction Log Physical Architecture.

For a log file, the current size is the same as the total size of the pages that are used by the virtual log files. Note, however, that pages are not used by the log files. Virtual log files that hold any part of the logical log cannot be freed. If all the virtual log files in a log file hold parts of...

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The vxtranslog command allows you to log VxVM transactions to a file.

The following examples demonstrate the usage of vxtranslog:

Transactions are logged to the file, translog, in the directory /etc/vx/log. This path name is a symbolic link to a directory whose location depends on the operating system. If required, you can redefine the directory which is linked. If you want to preserve the settings of the vxtranslog utility, you must also copy the settings file, .translog, to the new directory.

The size of the transaction log is checked after an entry has been written so the actual size may be slightly larger than that specified. When the log reaches a maximum size, the current transaction log file, translog, is renamed as the next available historic log file, translog.number, where number is an integer from 1 up to the maximum number of historic log files that is currently defined, and a new current log file is created.

A limited number of historic log...

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When SQL Server truncates the tranasction log, it only marks virtual log files that are no longer in use and already backed up (if running the full or bullk-logged recovery models) as reusable.

Say that a transaction log contains the following log records, and is using the simple recovery mode.

When a checkpoint now occurs, virtual log file 1 and 2 are no longer in use, as transactions 1 and 2 have been committed and the log records are not required to perform a rollback. SQL Server then marks virtual log file 1 and 2 are reusable, as follows:

This is what is known as truncating the transaction log. Basically, the active portion of the transaction log has been truncated. The physical size of the transaction log is unchanged, unless the database has the Autoshrink property set, in which case the transaction log will be physically shrunk (where possible) at periodic intervals.

So that's for the simple recovery model - once a...

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We’ll start with a brief review of the ideal storage architecture for the log file, for maximum log throughput, and then take a deeper look at how log fragmentation can affect the performance of operations that need to read the log, such as log backups, or the crash recovery process.

Finally, we’ll consider best practices in managing log sizing and growth, and the correct response to explosive log growth and fragmentation.

The correct physical hardware and architecture will help ensure that you get the best possible log throughput, and there are a few “golden rules.” Others have covered this before, notably Kimberly Tripp in her much-referenced blog post, 8 Steps to better Transaction Log throughput, so we won’t go into detail again here.

Note that in designing the underlying physical architecture for the log file, our primary goal is to optimize log write throughput. SQL Server writes to the log in response to every transaction that adds, removes or modifies...

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TimesTen supports transactions that provide atomic, consistent, isolated and durable (ACID) access to data. The following sections describe how you can configure transaction features.

Transaction overview

All operations on a TimesTen database, even those that do not modify or access application data, are executed within a transaction. When running an operation and there is no outstanding transaction, one is started automatically on behalf of the application. Transactions are completed by an explicit or implicit commit or rollback. When completed, resources that were acquired or opened by the transaction are released and freed, such as locks and cursors.

Use the following SQL statements to commit or rollback your transaction:

The SQL COMMIT statement commits the current transaction. Updates made in the transaction are made available to concurrent transactions.

The SQL ROLLBACK statement rolls back the current transaction. All updates made in...

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See also: SolrPerformanceFactors, SolrPerformanceData, BenchmarkingSolr

This page will attempt to answer questions like the following:

This is an attempt to give basic information only. For a better understanding of the issues involved, read the included links, look for other resources, and ask well thought out questions via Solr support resources.

There is a performance bug that makes *everything* slow in versions 6.4.0 and 6.4.1. The problem is fixed in 6.4.2. It is described by SOLR-10130. This is highly version specific, so if you are not running one of the affected versions, don't worry about it.

A major driving factor for Solr performance is RAM. Solr requires sufficient memory for two separate things: One is the Java heap, the other is "free" memory for the OS disk cache.

Another potential source of problems is a very high query rate. Adding memory can sometimes let Solr handle a higher rate. If more query scalability is required,...

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Each database contains at least one transaction log file. The transaction log records changes made to a database and stores sufficient information to allow changes to be undone (rolled back) or redone (rolled forward). This lesson covers the architecture of the transaction log, including the organization of transaction log files. This lesson also covers how the transaction log works and how the various recovery models affect the transaction log.

After this lesson, you will be able to

Understand the organization of transaction log files Understand how the transaction log functions Understand SQL Server 2000 recovery models View the properties of transaction log files

Estimated lesson time: 30 minutes

Introducing Transaction Log Files

Each SQL Server 2000 database has at least one transaction log file and can have multiple transaction log files spread across a number of...

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When we manage databases in either the FULL or BULK_LOGGED recovery models, we need to pay particular attention to the size of the transaction log files. If our processes aren't optimal, we can see log files grow either out of control, or beyond what we think is a reasonable size.

Virtual Log Files

As I mentioned in a previous post, the transaction log contains an ordered sequence of the physical operations that occur on a database.

What I didn't mention is that the physical transaction log file also contains logical sections, called virtual log files (VLFs). It's the VLFs which actually contain the physical operations I mentioned. The purpose of VLFs is to allow SQL Server to more efficiently manage the log records; specifically, to know which portions of the transaction log are used, and which aren't.

Knowing the portions of the log that are used is important when we go to take a transaction log backup, which creates a copy of all the transaction log...

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The problem lies in a specific parameter called the “block size limit.” The current limit is insufficient for the ever-growing transaction intensity.

First, a very quick and basic introduction to how Bitcoin works for those who don’t know. All the transactions that have ever taken place in the Bitcoin network or will ever take place, are recorded on a public and immutable ledger called “The Blockchain.”

As follows from its name, the Blockchain is a sequence of blocks. Each block, in turn, is a cryptographically sealed collection of all transactions which have happened in the network over the past ten minutes. Every new block is permanently added to the end of the Blockchain so that every user can always check that each specific transaction has indeed taken place.

Back in 2010, Nakamoto introduced a block size limit of 1mb, meaning that blocks over the size of 1 megabyte would be automatically rejected by the network as invalid. This was a security...

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Managing space on your SQL Server Transaction Log can sometimes be daunting, usually if you have a good backup strategy, and a well moderated database (in terms of monitoring and flagging long running transactions), then you will rarely run into unexpected large growth of your transaction log file. But in the real world this is rarely the case, and there will be occasions when you leave a very long transaction running over night (or days), or there is a schedule clash between two queries, or between a query and the backup schedule, which caused a failure in your log truncation strategy.

The daunting part is making sure that you recover from the situation with minimum data loss and disruption to the database’s recovery strategy. In this post I will go through the most common scenarios of transaction log growth, and how to resolve them.

There are a number of factors that can delay the truncation of the log file, these include:

A backup or a restore operation...
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Chapter 9: Configuring Transaction Logging


Transaction logs allow administrators to view the traffic that has passed through the Content Engine. Typical fields in the transaction log are the date and time when a request was made, the URL that was requested, whether it was a cache-hit or a cache-miss, the type of request, the number of bytes transferred, and the source IP.

High-performance caching presents additional challenges other than how to quickly retrieve objects from storage, memory, or the web. Administrators of caches are often interested in what requests have been made of the cache and what the results of these requests were. This information is then used for such applications as:

Problem identification and solving Load monitoring Billing Statistical analysis Security problems Cost analysis and provisioning

In ACNS 4.1 software, the user can choose between Squid, Extended Squid, and Apache log formats.


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Over time, with the use of SQL Server, the database transaction log file can grow quite large. This is actually normal and by design; however, it is not always the most desired behavior.

Using DBCC queries through SQL Server tools, you can force a resize of the database transaction log.

The following steps are confirmed to work on SQL Server 2005

Open "Microsoft SQL Server Management Studio" Switch the database recovery mode to "Simple".
This can be changed back after this procedure; however, keeping the recovery model "Simple" will help control the size of the transaction log. More information on database recovery models can be found here: Locate your database, and right click on it Select "Properties" On the left pane, select "Options" On the right pane, select "Simple" from the "Recovery Model" dropdown list. Click OK Create a new query: Click "New Query" on the toolbar. Execute in the...
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By Mark Strawmyer

Transaction logs are a vital yet often overlooked component of database architecture. They are often forgotten because they are not something actively maintained like the schema contained within a database. In this article we’ll examine how transaction logs are used in Microsoft SQL Server, maintenance and potential problems with them, how they can be used to restore a database, and finally, optimizing them for performance.

SQL Server transaction logs
A transaction log is a sequential record of all changes made to the database while the actual data is contained in a separate file. The transaction log contains enough information to undo all changes made to the data file as part of any individual transaction. The log records the start of a transaction, all the changes considered to be a part of it, and then the final commit or rollback of the transaction. Each database has at least one physical transaction log and one data file that is exclusive to...

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07/11/17 Lenovo publishes a new TPC-H result - 1,336,109 QphH@10,000GB - .92 USD/QphH@10,000GB - available: 10/19/2017

07/11/17 Lenovo publishes a new TPC-E result - 6,598.00 TpsE - 93.48 USD/TpsE - available: 10/19/2017

07/11/17 HPE publishes a new TPCx-BB result - 1,491.00 BBQpm@10000 - 589.91 USD/BBQpm@10000 - available:...

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A TP system is the computer system — both hardware and software — that hosts the transaction programs. The software...

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parts of a TP system usually are structured in a special way. As you can see from Figure 1.2 , the TP system has several main components. Different parts of the application execute in each of these components.

End-user device: An end user is someone who requests the execution of transactions, such as a customer of a bank or of an Internet retailer. An end-user device could be a physical device, such as a cash register or gasoline pump. Or it could be a web browser running on a desktop device, such as a...
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