2009/8/23 Itzchak Raiskin itzchak.rais...@gmail.com:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with all heights point along this
On 23/08/2009 3:08 PM, Itzchak Raiskin wrote:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with all heights point along this line.
Apologies for multiple posting - these extra copies were sent from
googlemail.com, whereas I has subscribed to the list as gmail.com.
Chris.
On Aug 19, 8:35 am, Chris Dew cms...@googlemail.com wrote:
http://www.sqlite.org/lang_savepoint.html
I'm looking for a datastore with the following
Hi, thanks for your questions.
1. restarts or OS crashes should leave the data in a sane state - the
last savepoint would be fine.
2. there's no requirement to revert to old savepoints set during a
previous application run.
3. no need for more than one process to access the data, though
letting
On Sun, 23 Aug 2009, Itzchak Raiskin wrote:
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height). I would like to query this
database with start and end points of a line and get a vector with all
heights point along this line. I
On Sun, Aug 23, 2009 at 01:08, Itzchak Raiskin itzchak.rais...@gmail.comwrote:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with
With these requirements you can't implement it just on database level
because it doesn't fit into the standard savepoint/transaction
paradigm of databases. Only committed data and finished transactions
will be available after OS crash or to other processes. After
transaction is committed it cannot
On Aug 23, 2009, at 6:46 AM, Chris Dew wrote:
Note: this is not for production code, just an experiment in keeping a
history of application 'state', allowing current state to be
recalculated if an historic input is received 'late'. See
On Sun, Aug 23, 2009 at 12:08 AM, Itzchak
Raiskinitzchak.rais...@gmail.com wrote:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with
On 23 Aug 2009, at 5:00pm, P Kishor wrote:
WHERE a*x - y + c = 0
Here's the problem. This works only when the equation is exact.
Which under normal circumstances means that all the numbers fit neatly
with some imaginary integer formula. This isn't how real life works,
especially when
Itzchak Raiskin wrote:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with all heights point along this line.
I can, of course
On Sun, Aug 23, 2009 at 11:11 AM, Simon
Slavinslav...@hearsay.demon.co.uk wrote:
On 23 Aug 2009, at 5:00pm, P Kishor wrote:
WHERE a*x - y + c = 0
Here's the problem. This works only when the equation is exact.
Indeed. We already laid out those presumptions. One, your height
coverage has to
On Sun, Aug 23, 2009 at 11:34 AM, P Kishorpunk.k...@gmail.com wrote:
On Sun, Aug 23, 2009 at 11:11 AM, Simon
Slavinslav...@hearsay.demon.co.uk wrote:
On 23 Aug 2009, at 5:00pm, P Kishor wrote:
WHERE a*x - y + c = 0
Here's the problem. This works only when the equation is exact.
Indeed.
On Sun, Aug 23, 2009 at 12:08 AM, Itzchak
Raiskinitzchak.rais...@gmail.com wrote:
Hi
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a line and
get a vector with
2009/8/23 P Kishor punk.k...@gmail.com:
If a line is expressed by (y = ax + c), you need to find all x,y that
will satisfy that equation. So,
SELECT x, y, z
FROM terrain
WHERE a*x - y + c = 0
General equation of line is a*x + b*y + c = 0. If you delete parameter
b, you will have a problem
hi all,
I am a kind of new to Sqlite and just wonder if the query result row could be
sorted by using Sqlite_prepare followed by Sqlite_Step.
For example, query statement is something like select * from sometable order
by somefield; and we call prepare followed by step. And are all results
nick huang wrote:
For example, query statement is something like select * from
sometable order by somefield; and we call prepare followed by step.
And are all results returned from step in order of somefield?
Of course. What would be the point of specifying order by somefield
otherwise?
As
Hello,
Is there a way to optimize this type of queries? (column Value is
indexed):
SELECT Value FROM MyValues WHERE Value LIKE '%crashed.'
I've seen the document where 'begins with' queries can be optimized
using = and (end of the '4.0 The LIKE optimization' section):
I want to use SQLite in a GIS application where I create a database
containing terrain data (coordinates, height).
I would like to query this database with start and end points of a
line and
get a vector with all heights point along this line.
I can, of course create a query for each point along
Hi Simon,
But that would introduce the overhead of doubling the space required
for every string + an additional column index. If the schema contains
more columns where this type of query needs to take place, it seems to
me that this would not be a good solution.
Thanks for your help,
--
On Mon, Aug 24, 2009 at 01:55:41AM +, nick huang scratched on the wall:
I am a kind of new to Sqlite and just wonder if the query result row
could be sorted by using Sqlite_prepare followed by Sqlite_Step.
Prepare/step is the only way to get data out of the database, so yes.
For
On 24 Aug 2009, at 3:44am, Tito Ciuro wrote:
Is there a way to optimize this type of queries? (column Value is
indexed):
SELECT Value FROM MyValues WHERE Value LIKE '%crashed.'
I've seen the document where 'begins with' queries can be optimized
using = and (end of the '4.0 The LIKE
On 24 Aug 2009, at 4:22am, Tito Ciuro wrote:
But that would introduce the overhead of doubling the space required
for every string + an additional column index.
One of the options I mentioned was to store the reversed string and
not the original. If you need to reconstruct the original
Hi Simon,
On Aug 23, 2009, at 8:52 PM, Simon Slavin wrote:
On 24 Aug 2009, at 4:22am, Tito Ciuro wrote:
But that would introduce the overhead of doubling the space required
for every string + an additional column index.
One of the options I mentioned was to store the reversed string and
On 24 Aug 2009, at 5:05am, Tito Ciuro wrote:
What I meant is that if a table contains several columns, some or all
of which need to be searched using 'ends with', then replicating the
columns (by reversing the string) and keeping extra indices could
potentially affect performance (obviously,
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