[sqlite] In the case of ZIPVFS

2015-12-23 Thread Michael Stephenson
Having just glanced at the documentation for ZIPVFS (didn't even know it existed)... 1) Perhaps using a real-time compression algorithm, something like lz4. It's not clear to me which algorithm ZIPVFS uses by default. 2) Perhaps increasing the cache settings to cache more pages in memory. 3)

[sqlite] In the case of ZIPVFS

2015-12-23 Thread 王庆刚
HI,all SQLite retrieves the compressed records is slower than the uncompressed records about 30%. How can improve the problem? and anyone any suggustion? best regards wqg

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
I know the reason why "PRAGMA mmap_size" could not improve the speed of retrieving records from ZIPVFS DB. However, I find sqlite3_soft_heap_limit64() , cache_szie and so on also which could not help improve the speed. Is all because of the ZIPVFS? At 2015-12-23 12:34:33, "Richard

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
Thank D. Richard Hipp very much. I can understand what you said. That is very helpful for me. Best regards At 2015-12-23 12:34:33, "Richard Hipp" wrote: >On 12/22/15, ??? <2004wqg2008 at 163.com> wrote: >>What do you mean of "render the mmap_size mote "? > >The "PRAGMA mmap_size"

[sqlite] whish list for 2016

2015-12-23 Thread lchis...@paradise.net.nz
Hi all, What I meant to ask was: a) Either an ORDER BY clause/equivalent for group_concat() [not GROUP BY as originally posted], or an assurance that the kludge of sorting a sub-query first and then grouping the result does and will continue to work - I need this functionality. This is what

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
>Setting the mmap_size will normally help read performance a lot. >However, if you are reading from a ZIPVFS database, the extra layer of >decryption and decompression that sits in between the disk and your >application will render the mmap_size mote - it won't matter. Thanks very much. What

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
>> >pragma mmap_size= 51200; >> >Pragma page_size = 8192; >> >Vacuum; >> >Pragma cache_size = N; The above code has nothing to do with the speed of retrieving records, especially the beginning retrieve records from database. Is this the right? At 2015-12-23 11:00:44, "???"

[sqlite] Query Regarding Shared Cache

2015-12-23 Thread Zeeshan Hussain
Hi All, We are using SQLite - Shared Cache for this we want to open two connection one from .Net and Another from C++ lib, both running in the same .Net process. Problem: It seems both the connections are using their own cache. even though we have opened them using same URI. Below is the

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
>How long does it take to retrieve one record from the database? >How long do you want it to take? The faster,the better. At 2015-12-23 10:58:13, "Keith Medcalf" wrote: > >How long does it take to retrieve one record from the database? >How long do you want it to take? > >> -Original

[sqlite] about compile configure

2015-12-23 Thread 王庆刚
>pragma mmap_size= 51200; >Pragma page_size = 8192; >Vacuum; >Pragma cache_size = N; The testing result shows that the above pragma statements could not improve the speed of retrieving records from data base. Best regards wqg At 2015-12-21 18:29:37, "Quan Yong Zhai" wrote: >pragma

[sqlite] In the case of ZIPVFS

2015-12-23 Thread Dominique Pellé
??? <2004wqg2008 at 163.com> wrote: > HI,all > SQLite retrieves the compressed records is slower than the uncompressed > records about 30%. > How can improve the problem? and anyone any suggustion? > > best regards > wqg What is your SQLite page size? If you access small

[sqlite] about compile configure

2015-12-23 Thread Simon Slavin
On 23 Dec 2015, at 4:46am, ??? <2004wqg2008 at 163.com> wrote: > sqlite3_soft_heap_limit64() , cache_szie and so on also which could not help > improve the speed These commands reduce the amount of memory your application uses. They will not help increase the speed unless you are repeatedly

[sqlite] In the case of ZIPVFS

2015-12-23 Thread Richard Hipp
On 12/23/15, ??? <2004wqg2008 at 163.com> wrote: > HI,all > SQLite retrieves the compressed records is slower than the uncompressed > records about 30%. > How can improve the problem? and anyone any suggustion? > Have you run your system in a profiler to determine where the extra 30%

[sqlite] Query Regarding Shared Cache

2015-12-23 Thread Richard Hipp
On 12/22/15, Zeeshan Hussain wrote: > Hi All, > > We are using SQLite - Shared Cache for this we want to open two connection > one from .Net and Another from C++ lib, both running in the same .Net > process. > > Problem: > It seems both the connections are using their own cache. even though we >