Selecting rows from one table not in another table
I have two tables
table_a_mod (2 million rows)
table_a (2 million rows + new live data)
table_a_mod is identical to table table_a except for two extra columns
table_a is a "live" table with data being written to it semi-regularly.
To keep table_a_mod up to date I would like to copy data from table_a to table_a_mod
By using a regular join, I am able to select the data:
SELECT *
FROM table_a t1
LEFT JOIN table_a_mod t2
USING(id)
WHERE t2.id IS NULL
However, this query takes about 1 minute to run.
Is there a more efficient query along the lines of:
SELECT *
FROM table_a t1
LEFT JOIN
(
SELECT id
FROM table_a_mod
ORDER BY id DESC
LIMIT 1
) t2
USING (id)
WHERE t1.id > t2.id
ie. Get the largest id from table t2. Select all rows from table t1 with id greater than that number.
I've tried different permutations of the above query but I'm falling short.
mysql
asked 11 mins ago
denormalizerdenormalizer
1011
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denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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I have two tables
table_a_mod (2 million rows)
table_a (2 million rows + new live data)
table_a_mod is identical to table table_a except for two extra columns
table_a is a "live" table with data being written to it semi-regularly.
To keep table_a_mod up to date I would like to copy data from table_a to table_a_mod
By using a regular join, I am able to select the data:
SELECT *
FROM table_a t1
LEFT JOIN table_a_mod t2
USING(id)
WHERE t2.id IS NULL
However, this query takes about 1 minute to run.
Is there a more efficient query along the lines of:
SELECT *
FROM table_a t1
LEFT JOIN
(
SELECT id
FROM table_a_mod
ORDER BY id DESC
LIMIT 1
) t2
USING (id)
WHERE t1.id > t2.id
ie. Get the largest id from table t2. Select all rows from table t1 with id greater than that number.
I've tried different permutations of the above query but I'm falling short.
mysql
asked 11 mins ago
denormalizerdenormalizer
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I have two tables
table_a_mod (2 million rows)
table_a (2 million rows + new live data)
table_a_mod is identical to table table_a except for two extra columns
table_a is a "live" table with data being written to it semi-regularly.
To keep table_a_mod up to date I would like to copy data from table_a to table_a_mod
By using a regular join, I am able to select the data:
SELECT *
FROM table_a t1
LEFT JOIN table_a_mod t2
USING(id)
WHERE t2.id IS NULL
However, this query takes about 1 minute to run.
Is there a more efficient query along the lines of:
SELECT *
FROM table_a t1
LEFT JOIN
(
SELECT id
FROM table_a_mod
ORDER BY id DESC
LIMIT 1
) t2
USING (id)
WHERE t1.id > t2.id
ie. Get the largest id from table t2. Select all rows from table t1 with id greater than that number.
I've tried different permutations of the above query but I'm falling short.
mysql
asked 11 mins ago
denormalizerdenormalizer
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I have two tables
table_a_mod (2 million rows)
table_a (2 million rows + new live data)
table_a_mod is identical to table table_a except for two extra columns
table_a is a "live" table with data being written to it semi-regularly.
To keep table_a_mod up to date I would like to copy data from table_a to table_a_mod
By using a regular join, I am able to select the data:
SELECT *
FROM table_a t1
LEFT JOIN table_a_mod t2
USING(id)
WHERE t2.id IS NULL
However, this query takes about 1 minute to run.
Is there a more efficient query along the lines of:
SELECT *
FROM table_a t1
LEFT JOIN
(
SELECT id
FROM table_a_mod
ORDER BY id DESC
LIMIT 1
) t2
USING (id)
WHERE t1.id > t2.id
ie. Get the largest id from table t2. Select all rows from table t1 with id greater than that number.
I've tried different permutations of the above query but I'm falling short.
mysql
mysql
asked 11 mins ago
denormalizerdenormalizer
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 11 mins ago
denormalizerdenormalizer
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 11 mins ago
denormalizerdenormalizer
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 11 mins ago
denormalizerdenormalizer
1011
asked 11 mins ago
denormalizerdenormalizer
1011
1011
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
denormalizer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
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