If the Phoenix system catalog table cannot be reached when a failure occurs, we force the server to be immediately aborted and failing this, call System. But if you have to split the log because of a server crash then you need to divide into suitable pieces, as described above in the "replay" paragraph.
One of the incoming fields must match the key defined in the mapping. You can tune the number of HFiles to compact and the frequency of a minor compaction however it is set to a to optimized default value.
Major Compaction reads all the Store files for a Region disable write ahead log hbase performance writes to a single Store file. Write-heavy workloads For write-heavy workloads where the primary key is monotonically increasing, create salt buckets to help avoid write hotspots, at the expense of overall read throughput due to the additional scans needed.
Type Data type of the column. However, the tradeoff for error-recovery is speed. Replaying a log is simply done by reading the log and adding the contained edits to the current MemStore. If deferred log flush is used, WAL edits are kept in memory until the flush period.
To explicitly flush the messages, call flushCommits. If you invoke this method while setting up for example a Put instance then the writing to WAL is forfeited! The only way to find orphaned rows in either table is to scan over all rows in the table and do a lookup in the other table for the corresponding row.
This means that each row will be transmitted to HBase as soon as it arrives at the step. As noted above, this is ok as we are only a very small bit behind and out of sync for very short periods Each data row and its index row s are guaranteed to to be written or lost - we never see partial updates as this is part of the atomicity guarantees of HBase.
This is an important design consideration driven by your requirements and use case.
However, to optimize for your particular environment and workload, there are several properties you can tune. The following parameters can be used with the Index Scrutiny Tool: The WAL is used as a lifeline to restore the status quo if the server goes down while data is being inserted. One thing to note is that regions from a crashed server can only be redeployed if the logs have been split and copied.
At read time, Phoenix will select the index table to use that will produce the fastest query time and directly scan it just like any other HBase table. In general, it is best to use WAL for Puts, and where loading throughput is a concern to use bulk loading techniques instead.
The used SequenceFile has quite a few shortcomings that need to be addressed. At the end an explicit flush of the MemStore note, this is not the flush of the log! This is common with time-series data such as log or event data, where once a row is written, it will never be updated.
Uses your primary key when appropriate. Due to licensing constraints, HBase does not ship with LZO compression libraries; these must be manually installed on each node if you want to use LZO compression.
Unsigned integer and unsigned long data can be stored directly without inverting the sign. All the following parameters must be set in hbase-site.
Then we have memstores delaying flushes because of too many storefiles memstores start getting bigger - our graph spike. If not supplied, then the column name is used.
But say you run a large bulk import MapReduce job that you can rerun at any time. Why not write all edits for a specific region into its own log file? The logs and ganglia showed that the flushes were happening well before MB still around MB "due to global heap pressure" - a sign that total memstores were consuming too much heap.
A useful pattern to speed up the bulk import process is to pre-create empty regions. The user may enter a number here in bytes.
Presplit regions for instant great performance Pre-splitting regions ensures that the initial load is more evenly distributed throughout the cluster, you should always consider using it if you know your key distribution beforehand.
It also prevents deadlocks by ensuring metadata rpc calls are processed with a higher priority than data rpc calls. If nothing is selected or only the name of the new table is definedthen the default of NONE is used for both compression and Bloom filters.
You would ask why that is the case? The Delete mapping button allows the current named mapping for the current named table to be deleted from the mapping table. This is a generic test of performance based on defaults - your results will vary based on hardware specs as well as you individual configuration.
Avoid major compaction at all cost Compaction is the process by which HBase cleans up after itself. You gain extra performance but need to take extra care that no data was lost during the import.By using the option to disable WAL (write-ahead log) on your LOAD statement, writes into HBase can be faster.
However, this is not a safe option. Turning off WAL can result in data loss if the region server crashes. Parent topic: Tuning HBase performance. In order to be closely consistent between read and write, I'm calling flush-commits on all the buffered tables at every 2 sec.
In my application, I place the HBase write call in a Queue (async manner) and draining the queue using 20 Consumer threads.
Distributed Log Replay Description: After a region server fails, we firstly assign a failed region to another region server with recovering state marked in ZooKeeper. Then a SplitLogWorker directly replays edits from WAL(Write-Ahead-Log)s of the failed region server.
The default behavior for Puts using the Write Ahead Log (WAL) is that HLog edits will be written immediately. If deferred log flush is used, WAL edits are kept in memory until the flush period.
If deferred log flush is used, WAL edits are kept in memory until the flush period. Best practices to optimize Phoenix performance.
Best practices to optimize Phoenix performance. The most important aspect of Phoenix performance is to optimize the underlying HBase.
Phoenix creates a relational data model atop HBase that converts SQL queries into HBase operations, such as scans.
consider disabling the write-ahead log. Disables writing to the Write Ahead Log (WAL). The WAL is used as a failsafe to restore the status quo if the server goes down while data is being inserted.
Disabling WAL will increase performance.Download