Fix Error “could not determine polymorphic type because input has type unknown” when using generate_subscripts() in PostgreSQL

If you’re getting an error that reads “could not determine polymorphic type because input has type unknown” when using the generate_subscripts() function in PostgreSQL, it’s probably because your first argument is of the wrong type.

The generate_subscripts() function requires an array as its first argument. Passing a non-array value will result in an error. The actual error can vary, depending on the argument you pass, but regardless, the error is usually due to a non-array argument being passed.

To fix this error, be sure to pass an array as the argument when calling generate_subscripts().

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Fix “sample size must be between…” Error when using array_sample() in PostgreSQL

If you’re getting an error that starts with “sample size must be between…” when using the array_sample() function in PostgreSQL, it’s probably because your second argument is either a negative value, or it’s larger than the number of elements in the array.

The second argument must be no less than zero, and it can’t be any larger than the number of elements in the array.

To fix this error, be sure that your second argument is greater than zero and less than or equal to the number of elements in the array at the first argument.

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Fix Error “function generate_subscripts(integer, integer) does not exist” in PostgreSQL

If you’re getting a PostgreSQL error that reads “function generate_subscripts(integer, integer) does not exist“, it’s probably because your first argument is not an array. This specific error message implies that the first argument is an integer, but we’d get a similar error when passing a numeric argument.

The first argument for this function must be an array.

To fix this error, be sure that your first argument to generate_subscripts() is an array.

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Fix “invalid input syntax for type integer…” When Using array_sample() in PostgreSQL

If you’re getting an error that reads “invalid input syntax for type integer…” when using the array_sample() function in PostgreSQL, it’s probably because your second argument is not an integer.

The second argument for this function must be an integer.

To fix this error, be sure that your second argument to array_sample() is an integer.

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Fix “could not determine polymorphic type because input has type unknown” Error When using array_sample() in PostgreSQL

If you’re getting an error that reads “could not determine polymorphic type because input has type unknown” when using the array_sample() function in PostgreSQL, it’s probably because your first argument is of the wrong type.

The array_sample() function requires an array as its first argument. Passing a non-array value will result in an error. The actual error can vary, depending on the argument you pass, but either way, the error is usually due to a non-array being passed.

To fix this error, be sure to pass an array as the first argument when calling the array_sample() function.

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Fix “function array_sample(integer, integer) does not exist” in PostgreSQL

If you’re getting an error that reads “function array_sample(integer, integer) does not exist” when using the array_sample() function in PostgreSQL, it’s probably because your first argument is not an array. In particular, this specific error message implies that the first argument is an integer.

The first argument for this function must be an array.

To fix this error, be sure that your first argument to array_sample() is an array, not an integer.

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Fix “Unknown event” Error in MySQL when Trying to Drop an Event

If you’re getting an error that reads something like “ERROR 1539 (HY000): Unknown event ‘Event1’” in MySQL when trying to drop an event, it’s probably because the event that you’re trying to drop doesn’t exist.

There are a couple of ways to address this issue. One way is to use the IF EXISTS clause so that dropping a non-existent event doesn’t cause an error. Another way is to check the name of the event that you’re trying to drop – it could be that you’re using the wrong event name.

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Fix “Variable ‘event_scheduler’ is a GLOBAL variable and should be set with SET GLOBAL” in MySQL

If you’re getting an error that reads “ERROR 1229 (HY000): Variable ‘event_scheduler’ is a GLOBAL variable and should be set with SET GLOBAL” in MySQL, it’s probably because you’re trying to set the event_scheduler system variable, but you’re not specifying it as a global variable.

The event_scheduler variable is a global variable and so we must specify it as a global variable.

To fix this issue, specify it as a global variable when setting it’s value.

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4 Ways to Fix the “Failed to generate invisible primary key. Column ‘my_row_id’ already exists” Error in MySQL

If you’re getting an error that reads “Failed to generate invisible primary key. Column ‘my_row_id’ already exists“, it’s probably because you’re trying to create a table without a primary key, and you’ve named a column my_row_id.

When your system has generated invisible primary keys (GIPKs) enabled, and you create an InnoDB table without explicitly defining a primary key, MySQL automatically creates an invisible column called my_row_id and creates a primary key constraint against it. This is called a generated invisible primary key.

However, if you name one of your columns my_row_id, then MySQL can’t create the GIPK due to the column already existing.

There are several ways to go about fixing this issue.

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Fix “Multiple primary key defined” Error in MySQL

If you’re getting an error that reads something like “Multiple primary key defined” in MySQL, it’s probably because you’re defining more than one primary key to a table.

A table can only have one primary key in MySQL.

It’s possible that you were trying to create a composite primary key (i.e. a primary key consisting of multiple columns), in which case, you can fix the issue with a simple modification to your code.

Otherwise, you will need to decide which column should be the primary key for the table and only apply the PRIMARY KEY definition to that column.

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