Initial commit

2020-06-15 10:58:47 +08:00
commit 4f1dfe7564
8590 changed files with 1516878 additions and 0 deletions
@@ -0,0 +1,44 @@
+## Column names normalization
+
+When data is uploaded into CARTO using the Import API, the resulting dataset in CARTO might have different column names than the original dataset.
+
+This is because as part of the import workflow there's a process to normalize the column names to avoid unsupported column names in the datasets created after the import process finishes. Some of the actions taken when normalizing column names are:
+
+- Remove accents
+- Convert multiple consecutive underscores and hyphens to a single underscore
+- Remove unsupported characters ([]{}&%$+, etc.)
+- Remove white spaces
+- Avoid duplicated column names
+- Avoid column names longer than 63 characters
+- Avoid reserved words
+- Force lower case names
+- Force column names to start by a character
+
+### Some examples of column name normalization
+
+Find below a table with some examples of column names and how they are normalized by the Import API:
+
+| *original column name* | *normalized column name* |
+| Field: 2 | field_
+| 2 Items | _2_item
+| Unnamed: 0 | unnamed_0
+| 201moore | _201moore
+| 201moore | _201moore_1
+| Acadia 1.2.3 | acadia_1_2_3
+| _testingTesting | _testingtesting
+| 1 | _1
+| 1.0 | _1_0
+| SELECT | _select
+| à | a
+| longcolumnshouldbesplittedsomehowanditellyouwhereitsgonnabesplittedrightnow | longcolumnshouldbesplittedsomehowanditellyouwhereitsgonnabespli 
+| longcolumnshouldbesplittedsomehowanditellyouwhereitsgonnabesplittedrightnow | longcolumnshouldbesplittedsomehowanditellyouwhereitsgonnabe_1 
+| all | _all
+
+### Changing column names
+
+In some cases you may want to preserve some of the column names in your original data. For example, let's say you have a column name `column__1` which indeed is a valid column name for PostgreSQL and the Import API renamed it as `column_1`. In the case you want to preserve `column__1` as the column name, right after the import process finished you can update the column name using the [CARTO SQL API](https://carto.com/developers/sql-api/) with a query like this:
+
+```sql
+  ALTER TABLE test_1 RENAME COLUMN column_1 to column__1;
+  SELECT CDB_TableMetadataTouch('test_1');
+```