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MySQL Great Circle Distance (Haversine formula)
...latitude in degrees',
`lon` FLOAT NOT NULL COMMENT 'longitude in degrees',
INDEX `lat_lon_idx` (`lat`, `lon`)
)
If you're using TokuDB, you'll get even better performance if you add clustering
indexes on either of the predicates, for example, like this:
alter table Coordinates add clustering ...
Physical vs. logical / soft delete of database record?
...siness needs.
EDIT: Thought of another disadvantange - If you have unique indexes on the table, deleted records will still take up the "one" record, so you have to code around that possibility too (for example, a User table that has a unique index on username; A deleted record would still block the...
When to use MyISAM and InnoDB? [duplicate]
...s much less costs of server resources. -- Mostly no longer true.
Full-text indexing. -- InnoDB has it now
Especially good for read-intensive (select) tables. -- Mostly no longer true.
Disk footprint is 2x-3x less than InnoDB's. -- As of Version 5.7, this is perhaps the only real advantage of MyISA...
efficient circular buffer?
...nderstandable when the deque can grow to infinity, but if maxlen is given, indexing an element should be constant time.
– lvella
Nov 13 '15 at 21:57
1
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Creating range in JavaScript - strange syntax
...arr);
Number(i, arr);
Which returns the transformation of i, the current index, to a number.
In conclusion,
The expression
Array.apply(null, { length: 5 }).map(Number.call, Number);
Works in two parts:
var arr = Array.apply(null, { length: 5 }); //1
arr.map(Number.call, Number); //2
The fi...
Deleting DataFrame row in Pandas based on column value
...df[df.columns[2].notnull()], but one way or another you need to be able to index the column somehow.
– erekalper
Nov 9 '18 at 20:35
1
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Bash script to cd to directory with spaces in pathname
...
When you double-quote a path, you're stopping the tilde expansion. So there are a few ways to do this:
cd ~/"My Code"
cd ~/'My Code'
The tilde is not quoted here, so tilde expansion will still be run.
cd "$HOME/My Code"
You can expand ...
How to grab substring before a specified character jQuery or JavaScript
...xtract everything before the ',' comma. How do I do this in JavaScript or jQuery? I tried this and not working..
11 Answers...
Computed / calculated / virtual / derived columns in PostgreSQL
...e to list it explicitly.
Can also be supported with a matching expression index - provided the function is IMMUTABLE. Like:
CREATE FUNCTION col(tbl) ... AS ... -- your computed expression here
CREATE INDEX ON tbl(col(tbl));
Alternatives
Alternatively, you can implement similar functionality wi...
AngularJS For Loop with Numbers & Ranges
...this. It should be a new attribute that works with two values. The current index and the upper bound.
– Ian Warburton
May 19 '13 at 18:49
10
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