We have added a new SQL command that works with VServer only to show tail of VServer.log file. (5.0b30)
TODO Valentina Studio now have a special panel where user can easy see this log using new command.
All together this simplify a lots work with remote VServer, especially if you do not have SSH access to its file system.
We have extend SHOW DATABASES command to show also not registered databases located in the VServer/databases folder. To implement this VServer now is able iterate this folder to see files with .vdb extension.
Valentina Studio now take this in attention and show such not registered databases with a special icon. Also you get contextual menu with command “Register database”.
Refresh button of VStudio is able issue SHOW DATABASE command to check folder for new files if needed.
After some benches we have discover that loop on small joins (when only one record on the left and few on the right) is not fast enough.
We have two major algorithms internally and we have discover that the first takes only 50 seconds on 10000 loops, while the second takes hundreds of seconds…So problem presents in the second algorithm.
Improved.
Now the second algorithm takes 120 second. And we can add yet choice condition to choose the first for such case of small joins…
I think we will be able to improve the second alg yet to 70-80 sec. And may be with more complex changes it is possible to speed both after that …
After some benches we have discover that it is not a good idea to use ZIP compression of data if VServer is on localhost or on fast LAN.
To resolve this we have specify 3 possible steps and made the first one without changes in API. As result, now VClient and VServer automatically can do raw analyze of network and define if to use ZIP.
Future we will add even special VClient function VConnection.Tune(), which your app can call on start, and later each 30 min for example to measure and analyze network state more accurately.
Here we show couple of few-seconds movies that demonstrate how you can establish links between tables using new diagrams of Valentina Studio Pro.
For Valentina database you can establish Foreign Key, ObjectPtr and Binary Link. For SQLite and Postgre only Foreign Key.
Shows how you get access to “Add Link” button and then to panel, which allows you to choose link type for the left and right table.
Shows how you can establish by few mouse clicks MM link between two tables, and how this automatically creates third MM table and FK fields in original table(s).
We have made a couple of benches of our new SQL DIFF feature of Valentina Studio Pro v5.0 Results are quite impressive.
Starting from v.5.0, you may get count of affected links (pair of records affected by LINK/UNLINK… statement) via QueryResult::get_AsULong()
Thorsten have point us that for his task it is not comfortable when command
LINK RECORD (1) OF T1 TO RECORDS(3, 7, 9) OF T2
throws error and stops, if link 1-7 already exists.
We have agree and improve these commands adding suffix
LINK … [IF NOT EXISTS]
UNLINK … [IF EXISTS]
This suffix is similar to CREATE/DROP commands. If it is specified, then error is not fired and command continue work for other pairs of links.
Thorsten have point us that WIKI page about this command looks strange, because uses
Referential_action
: NO ACTION (alias to RESTRICT)
| RESTRICT
| SET NULL
| SET DEFAULT
| CASCADE
Now SQL grammar have one more rule vext_referential_action_for_link without “SET NULL”, “SET DEFAULT” and added “NO CADCADE” for Binary Links.
While Valentina have very cool syntax for recursive queries, one Valentina developer have point us that it cannot be used in his task, because he do not have predefined link with name. Taking this into account, for v5.0 we have extend syntax of recursive query
from USING link_name
to USING (link_name | search_condtiion)
Continue reading [IMP] Recursive query now can use RDB-link defined on the fly
This is expected improvement similar to INSERT and LINK commands. Now you can do
“SET PROPERTY x, y, z OF TABLE T TO :1, :2, :3”
Each Valentina’s volume consists of set of segments, even internal service-data placed in such segments.
Database storage is implemented similar to some file system. There are volumes (.vdb, .dat, .blb, .ind, .tmp) and there are some embedded files on that volumes (all the data like field-data, indexes and so on go to that files). Each volume operates with own segment map – so we can find (and allocate new) segments for particular embedded file easy and fast.
Continue reading Choosing appropriate database’s segment size
To improve CLONE command with ability to change some properties of cloned database we have extend CLONE DATABASE command with optional suffix [WITH vext_set_property] exactly like in CREATE DATABASE command.
Reason why we did this is described in details in the article “Choosing appropriate database’s segment size“.