Hi, That’s right, Ignite nodes restart “cold” meaning that they become operational without the data in the RAM. It allows to restart as quickly as possible, but the price is that the first operations have to load data from the disk, meaning that the performance will be much lower.
Here is a ticket to allow turn on a “hot restart” mode - https://issues.apache.org/jira/browse/IGNITE-10152. There is also an improvement that allows to manually load data of a specific partition in an efficient way - https://issues.apache.org/jira/browse/IGNITE-8873. If you iterate over all partitions after the node start it may shorten the warmup period. Stan From: Glenn Wiebe Sent: 8 января 2019 г. 18:02 To: user@ignite.apache.org Subject: Re: Ignite 2.7 Persistence I am new to Ignite, but as I understand it, after cluster restart, data is re-hydrated into memory as the nodes receive requests for their partitions' entries. So, a first query would be as slow as a distributed disk-based query. Subsequent queries should have some (depending on memory available) information in memory and thus faster. So, my question, is this the first query execution since startup? Given that you have sufficient memory to hold this particular cache, I would expect subsequent query executions to take advantage of memory resident query processing. Additionally I have done a quick look (but could not find) at whether Ignite caches in memory store aggregates (like counts) which may be able to be returned without reading actual data as here. Good luck! On Tue, Jan 8, 2019 at 7:55 AM gweiske <gwei...@eagleinvsys.com> wrote: I am using Ignite 2.7 with persistence enabled on a single VM with 128 GB RAM in Azure and separate external HDD drives each for wal, walarchive and storage. I loaded 20 GB of data/50,000,000 rows, then shut down Ignite and restarted the hosting VM, started and activated Ignite and ran a simple query that requires sorting through all the data (SELECT DISTINCT <column> FROM ;). The query has been running for hours now. Looking at the memory, instead of the expected ~42 GB it is currently at 5.7GB (*slowly* increasing). Any ideas why it might be that slow? The same scenario with SSD drives (this time 1 drive for wal and walarchive, a second one for storage) finishes in about 5500 seconds (still slow). -- Sent from: http://apache-ignite-users.70518.x6.nabble.com/
