Where to index - over 15m records and growing
Hi All, I have a huge issue with a query - it copies the entire table to a tmp table when executing the query - and it's a big ass table Any help and/or pointers please? The query: SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; FlightRoutes: mysql DESCRIBE FlightRoutes; +--++--+-+-+---+ | Field| Type | Null | Key | Default | Extra | +--++--+-+-+---+ | FlightID | char(36) | NO | PRI | NULL| | | Dep | varchar(5) | NO | MUL | NULL| | | Des | varchar(5) | NO | | NULL| | | Route| text | NO | | NULL| | +--++--+-+-+---+ 4 rows in set (0.00 sec) mysql SHOW INDEX IN FlightRoutes; +--+++--+-+---+-+--++--++-+ | Table| Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +--+++--+-+---+-+--++--++-+ | FlightRoutes | 0 | PRIMARY|1 | FlightID| A | 106216 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |1 | Dep | A |3124 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |2 | Des | A | 26554 | NULL | NULL | | BTREE | | +--+++--+-+---+-+--++--++-+ 3 rows in set (0.00 sec) IVAOData: mysql DESCRIBE IVAOData; +---+--+--+-+-+---+ | Field | Type | Null | Key | Default | Extra | +---+--+--+-+-+---+ | EntryID | char(36) | NO | PRI | NULL| | | FlightID | char(36) | NO | MUL | NULL| | | isProcessed | enum('0','1')| NO | MUL | NULL| | | TrackerTime | int(10) unsigned | NO | MUL | NULL | | | CallSign | varchar(10) | NO | | NULL| | | VID | mediumint(6) unsigned| NO | MUL | NULL| | | RealName | tinytext | NO | | NULL| | | ClientType| enum('ACT','PILOT','FOLME') | NO | | NULL| | | Latitude | float(8,5) | NO | | NULL| | | Longitude | float(9,5) | NO | | NULL| | | Altitude | smallint(5) unsigned | NO | | NULL| | | GroundSpeed | smallint(5) unsigned | NO | | NULL| | | PlannedAircraft | varchar(30) | NO | | NULL| | | PlannedTASCruise | varchar(10) | NO | | NULL| | | PlannedDepAirport | varchar(5) | NO | | NULL| | | PlannedAltitude | varchar(5) | NO | | NULL| | | PlannedDestAirport| varchar(5) | NO | | NULL| | | Server| char(3) | NO | | NULL| | | Rating| enum('1','2','3','4','5','6','7','8','9','10','11','12') | NO | | NULL| | | Transponder | smallint(4) unsigned zerofill| NO | | NULL| | | PlannedFlightType | enum('','I','V','Y','Z') | NO | |
Re: Where to index - over 15m records and growing
Hey Chris, Please send the explain plan for this query, the estimated table sizes (in MB or GB) and the RAM capacity. These are also the requisites for helping optimizing your query if required... Thanks. Anirudh Sundar On Fri, May 7, 2010 at 12:14 PM, Chris Knipe sav...@savage.za.org wrote: Hi All, I have a huge issue with a query - it copies the entire table to a tmp table when executing the query - and it's a big ass table Any help and/or pointers please? The query: SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; FlightRoutes: mysql DESCRIBE FlightRoutes; +--++--+-+-+---+ | Field| Type | Null | Key | Default | Extra | +--++--+-+-+---+ | FlightID | char(36) | NO | PRI | NULL| | | Dep | varchar(5) | NO | MUL | NULL| | | Des | varchar(5) | NO | | NULL| | | Route| text | NO | | NULL| | +--++--+-+-+---+ 4 rows in set (0.00 sec) mysql SHOW INDEX IN FlightRoutes; +--+++--+-+---+-+--++--++-+ | Table| Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +--+++--+-+---+-+--++--++-+ | FlightRoutes | 0 | PRIMARY|1 | FlightID| A | 106216 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |1 | Dep | A |3124 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |2 | Des | A | 26554 | NULL | NULL | | BTREE | | +--+++--+-+---+-+--++--++-+ 3 rows in set (0.00 sec) IVAOData: mysql DESCRIBE IVAOData; +---+--+--+-+-+---+ | Field | Type | Null | Key | Default | Extra | +---+--+--+-+-+---+ | EntryID | char(36) | NO | PRI | NULL| | | FlightID | char(36) | NO | MUL | NULL| | | isProcessed | enum('0','1')| NO | MUL | NULL| | | TrackerTime | int(10) unsigned | NO | MUL | NULL | | | CallSign | varchar(10) | NO | | NULL| | | VID | mediumint(6) unsigned| NO | MUL | NULL| | | RealName | tinytext | NO | | NULL| | | ClientType| enum('ACT','PILOT','FOLME') | NO | | NULL| | | Latitude | float(8,5) | NO | | NULL| | | Longitude | float(9,5) | NO | | NULL| | | Altitude | smallint(5) unsigned | NO | | NULL| | | GroundSpeed | smallint(5) unsigned | NO | | NULL| | | PlannedAircraft | varchar(30) | NO | | NULL| | | PlannedTASCruise | varchar(10) | NO | | NULL| | | PlannedDepAirport | varchar(5) | NO | | NULL| | | PlannedAltitude | varchar(5) | NO | | NULL| | | PlannedDestAirport| varchar(5) | NO | | NULL| | | Server| char(3)
Re: Where to index - over 15m records and growing
My appologies for leaving that bit out... mysql EXPLAIN SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; ++-+--+---+---++-+---++-+ | id | select_type | table| type | possible_keys | key| key_len | ref | rows | Extra | ++-+--+---+---++-+---++-+ | 1 | SIMPLE | FlightRoutes | index | PRIMARY | ixAirports | 14 | NULL | 106216 | Using temporary; Using filesort | | 1 | SIMPLE | IVAOData | ref | ixFlightID,ixTime | ixFlightID | 36 | tracker.FlightRoutes.FlightID | 73 | Using where | ++-+--+---+---++-+---++-+ 2 rows in set (0.33 sec) Table / Index Sizes: r...@netsonic:/var/lib/mysql/tracker# ls -lah IVAOData.* FlightRoutes.* -rw-rw 1 mysql mysql 8.5K 2010-04-30 08:57 FlightRoutes.frm -rw-rw 1 mysql mysql 9.7M 2010-05-07 01:13 FlightRoutes.MYD -rw-rw 1 mysql mysql 6.1M 2010-05-07 01:39 FlightRoutes.MYI -rw-rw 1 mysql mysql 11K 2010-05-06 11:23 IVAOData.frm -rw-rw 1 mysql mysql 3.9G 2010-05-07 09:19 IVAOData.MYD -rw-rw 1 mysql mysql 1.4G 2010-05-07 09:19 IVAOData.MYI I expect the IVAOData table to roughly tripple in size. Currently it holds 2 months worth of data, the ideal situation would be to keep 6 months worth of data in the table... RAM Size on the machine is 8GB... Regards, Chris. On Fri, May 7, 2010 at 9:17 AM, Anirudh Sundar sundar.anir...@gmail.comwrote: Hey Chris, Please send the explain plan for this query, the estimated table sizes (in MB or GB) and the RAM capacity. These are also the requisites for helping optimizing your query if required... Thanks. Anirudh Sundar On Fri, May 7, 2010 at 12:14 PM, Chris Knipe sav...@savage.za.org wrote: Hi All, I have a huge issue with a query - it copies the entire table to a tmp table when executing the query - and it's a big ass table Any help and/or pointers please? The query: SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; FlightRoutes: mysql DESCRIBE FlightRoutes; +--++--+-+-+---+ | Field| Type | Null | Key | Default | Extra | +--++--+-+-+---+ | FlightID | char(36) | NO | PRI | NULL| | | Dep | varchar(5) | NO | MUL | NULL| | | Des | varchar(5) | NO | | NULL| | | Route| text | NO | | NULL| | +--++--+-+-+---+ 4 rows in set (0.00 sec) mysql SHOW INDEX IN FlightRoutes; +--+++--+-+---+-+--++--++-+ | Table| Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +--+++--+-+---+-+--++--++-+ | FlightRoutes | 0 | PRIMARY|1 | FlightID| A | 106216 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |1 | Dep | A |3124 | NULL | NULL | | BTREE | | | FlightRoutes | 1 | ixAirports |2 | Des | A | 26554 | NULL | NULL | | BTREE | | +--+++--+-+---+-+--++--++-+ 3 rows in set (0.00 sec) IVAOData: mysql DESCRIBE IVAOData; +---+--+--+-+-+---+ | Field | Type
Re: Where to index - over 15m records and growing
Added whitespace for readabilty: SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; First thing that pops to mind: Do you *really* mean left join? Second thing: How selective is WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') Test by running SELECT COUNT(*) FROM IVAOData WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') If this is a large proportion of the row count then you are probably in store for pain. It sounds like you are matching half the table. Big (intermediate) result sets often end in pain. Third thing: My (rather sleepy) gut thinks your best bet is a a composite index on the table IVAOData on the columns TrackerTime and FlightID. This will make all access to the table in this query hit a covering index. Fourth thing: What do you intend to ask the database with this query. This query smells overly broad. -- Rob Wultsch wult...@gmail.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org
Re: Where to index - over 15m records and growing
On Fri, May 7, 2010 at 10:42 AM, Rob Wultsch wult...@gmail.com wrote: Second thing: How selective is WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') Test by running SELECT COUNT(*) FROM IVAOData WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') If this is a large proportion of the row count then you are probably in store for pain. It sounds like you are matching half the table. Big (intermediate) result sets often end in pain. At this stage, you are correct. We have roughly 2 months worth of data in the table and are selecting about half (one months worth), thus about 50%. With 6 months worth of data in the table and selecting one months worth of data, that's roughly 16% of the data - but it will still be a bulk large result... Hmmm, something tells me I need to rethink this yes. Third thing: My (rather sleepy) gut thinks your best bet is a a composite index on the table IVAOData on the columns TrackerTime and FlightID. This will make all access to the table in this query hit a covering index. Took over 12 hours to create the index on TrackerTime, and you're right - I should have seen and realised this. I will drop the index on TrackerTime and re-create it using both colums as I should have done in the first place. Fourth thing: What do you intend to ask the database with this query. This query smells overly broad The idea is to get a count of the number of entries from Dep to Des during the last month. I.E. How many records are there where Dep and Des are the same during the last month. With some changes to the application that captures the data in the first place, I should be able to drop the need for this query completely. You have made me think a bit here and you're right. This is not the way to do it. I'll rethink this a bit more and come up with something better. PS - Started the query before my first email was even posted, it's still running... 3948 Seconds the last time I checked... -- Regards, Chris Knipe
Re: Where to index - over 15m records and growing
something tells me I need to rethink this yes. If you were to add a computed column yearmonth, you could write WHERE yearmonth=201004. PB - Chris Knipe wrote: On Fri, May 7, 2010 at 10:42 AM, Rob Wultsch wult...@gmail.com wrote: Second thing: How selective is WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') Test by running SELECT COUNT(*) FROM IVAOData WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') If this is a large proportion of the row count then you are probably in store for pain. It sounds like you are matching half the table. Big (intermediate) result sets often end in pain. At this stage, you are correct. We have roughly 2 months worth of data in the table and are selecting about half (one months worth), thus about 50%. With 6 months worth of data in the table and selecting one months worth of data, that's roughly 16% of the data - but it will still be a bulk large result... Hmmm, something tells me I need to rethink this yes. Third thing: My (rather sleepy) gut thinks your best bet is a a composite index on the table IVAOData on the columns TrackerTime and FlightID. This will make all access to the table in this query hit a covering index. Took over 12 hours to create the index on TrackerTime, and you're right - I should have seen and realised this. I will drop the index on TrackerTime and re-create it using both colums as I should have done in the first place. Fourth thing: What do you intend to ask the database with this query. This query smells overly broad The idea is to get a count of the number of entries from Dep to Des during the last month. I.E. How many records are there where Dep and Des are the same during the last month. With some changes to the application that captures the data in the first place, I should be able to drop the need for this query completely. You have made me think a bit here and you're right. This is not the way to do it. I'll rethink this a bit more and come up with something better. PS - Started the query before my first email was even posted, it's still running... 3948 Seconds the last time I checked... No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.437 / Virus Database: 271.1.1/2859 - Release Date: 05/07/10 06:26:00
Re: Where to index - over 15m records and growing
You could be running into this: http://dev.mysql.com/doc/refman/5.0/en/how-to-avoid-table-scan.html On Fri, May 7, 2010 at 10:05 AM, Peter Brawley peter.braw...@earthlink.netwrote: something tells me I need to rethink this yes. If you were to add a computed column yearmonth, you could write WHERE yearmonth=201004. PB - Chris Knipe wrote: On Fri, May 7, 2010 at 10:42 AM, Rob Wultsch wult...@gmail.com wrote: Second thing: How selective is WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') Test by running SELECT COUNT(*) FROM IVAOData WHERE IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime =UNIX_TIMESTAMP('2010-04-30 23:59:50') If this is a large proportion of the row count then you are probably in store for pain. It sounds like you are matching half the table. Big (intermediate) result sets often end in pain. At this stage, you are correct. We have roughly 2 months worth of data in the table and are selecting about half (one months worth), thus about 50%. With 6 months worth of data in the table and selecting one months worth of data, that's roughly 16% of the data - but it will still be a bulk large result... Hmmm, something tells me I need to rethink this yes. Third thing: My (rather sleepy) gut thinks your best bet is a a composite index on the table IVAOData on the columns TrackerTime and FlightID. This will make all access to the table in this query hit a covering index. Took over 12 hours to create the index on TrackerTime, and you're right - I should have seen and realised this. I will drop the index on TrackerTime and re-create it using both colums as I should have done in the first place. Fourth thing: What do you intend to ask the database with this query. This query smells overly broad The idea is to get a count of the number of entries from Dep to Des during the last month. I.E. How many records are there where Dep and Des are the same during the last month. With some changes to the application that captures the data in the first place, I should be able to drop the need for this query completely. You have made me think a bit here and you're right. This is not the way to do it. I'll rethink this a bit more and come up with something better. PS - Started the query before my first email was even posted, it's still running... 3948 Seconds the last time I checked... No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.437 / Virus Database: 271.1.1/2859 - Release Date: 05/07/10 06:26:00 -- - Johnny Withers 601.209.4985 joh...@pixelated.net
Re: Where to index - over 15m records and growing
Hello Chris, Your Query Build EXPLAIN SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; My Query Build -- EXPLAIN SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime between UNIX_TIMESTAMP('2010-04-01 00:00:00') AND UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; Suggestions :- 1. Do some research on Query caching because both the tables used are MYISAM, Query Cache can be useful on MYISAM tables (Provided query build values are static). 2. Run Analyze and Optimize commands on the IVAOData table. It will help updating the index statictics and defragmenting the table (the table will respond better to queries). try these can get back with your observations. Cheers, Anirudh Sundar On Fri, May 7, 2010 at 12:51 PM, Chris Knipe sav...@savage.za.org wrote: My appologies for leaving that bit out... mysql EXPLAIN SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; ++-+--+---+---++-+---++-+ | id | select_type | table| type | possible_keys | key | key_len | ref | rows | Extra | ++-+--+---+---++-+---++-+ | 1 | SIMPLE | FlightRoutes | index | PRIMARY | ixAirports | 14 | NULL | 106216 | Using temporary; Using filesort | | 1 | SIMPLE | IVAOData | ref | ixFlightID,ixTime | ixFlightID | 36 | tracker.FlightRoutes.FlightID | 73 | Using where | ++-+--+---+---++-+---++-+ 2 rows in set (0.33 sec) Table / Index Sizes: r...@netsonic:/var/lib/mysql/tracker# ls -lah IVAOData.* FlightRoutes.* -rw-rw 1 mysql mysql 8.5K 2010-04-30 08:57 FlightRoutes.frm -rw-rw 1 mysql mysql 9.7M 2010-05-07 01:13 FlightRoutes.MYD -rw-rw 1 mysql mysql 6.1M 2010-05-07 01:39 FlightRoutes.MYI -rw-rw 1 mysql mysql 11K 2010-05-06 11:23 IVAOData.frm -rw-rw 1 mysql mysql 3.9G 2010-05-07 09:19 IVAOData.MYD -rw-rw 1 mysql mysql 1.4G 2010-05-07 09:19 IVAOData.MYI I expect the IVAOData table to roughly tripple in size. Currently it holds 2 months worth of data, the ideal situation would be to keep 6 months worth of data in the table... RAM Size on the machine is 8GB... Regards, Chris. On Fri, May 7, 2010 at 9:17 AM, Anirudh Sundar sundar.anir...@gmail.comwrote: Hey Chris, Please send the explain plan for this query, the estimated table sizes (in MB or GB) and the RAM capacity. These are also the requisites for helping optimizing your query if required... Thanks. Anirudh Sundar On Fri, May 7, 2010 at 12:14 PM, Chris Knipe sav...@savage.za.orgwrote: Hi All, I have a huge issue with a query - it copies the entire table to a tmp table when executing the query - and it's a big ass table Any help and/or pointers please? The query: SELECT COUNT(FlightRoutes.FlightID) AS Count, FlightRoutes.Dep AS Dep, FlightRoutes.Des AS Des FROM FlightRoutes LEFT JOIN IVAOData ON FlightRoutes.FlightID=IVAOData.FlightID WHERE IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-01 00:00:00') AND IVAOData.TrackerTime = UNIX_TIMESTAMP('2010-04-30 23:59:50') GROUP BY FlightRoutes.Dep, FlightRoutes.Des ORDER BY COUNT(FlightRoutes.FlightID) LIMIT 20; FlightRoutes: mysql DESCRIBE FlightRoutes; +--++--+-+-+---+ | Field| Type | Null | Key | Default | Extra | +--++--+-+-+---+ | FlightID | char(36) | NO | PRI | NULL| | | Dep | varchar(5) | NO | MUL | NULL| | | Des | varchar(5) | NO | | NULL| | | Route| text | NO |