Tables / ERD
The, imho, most important tables and attributes are depicted in the following graphic (drawn with draw.io): 
postType
There are 8 post types
| id | name |
| 1 | Question |
| 2 | Answer |
| 3 | Wiki |
| 4 | TagWikiExcerpt |
| 5 | TagWiki |
| 6 | ModeratorNomination |
| 7 | WikiPlaceholder |
| 8 | PrivilegeWiki |
voteTypes
There are 14 vote types
| id | name |
| 1 | AcceptedByOriginator |
| 2 | UpMod |
| 3 | DownMod |
| 4 | Offensive |
| 5 | Favorite |
| 6 | Close |
| 7 | Reopen |
| 8 | BountyStart |
| 9 | BountyClose |
| 10 | Deletion |
| 11 | Undeletion |
| 12 | Spam |
| 15 | ModeratorReview |
| 16 | ApproveEditSuggestion |
tagSynonyms
The following SQL statement returns no records. Thus, the attribute
sourceTagName is shown to be unique: select count(*) cnt, sourceTagName from tagSynonyms group by sourceTagName having count(*) > 1
Github repository data-stackexchange, path: /erd/analysis/tagSynonyms-uniqueSourceTagName.sql
Both,
sourceTagName and targetTagName are found in the tags table. As of 2019-03-19, the table tagSynonyms had 4437 records of which 1387 could be joined to tagSynonyms via sourceTagName and 4365 via targetTagName. select count(syn.id) cntSynonyms, count(tag.id) cntFoundSourceTagNames from tagSynonyms syn left join tags tag on syn.sourceTagname = tag.tagName
Github repository data-stackexchange, path: /erd/analysis/tagSynonyms-joinSourceTagName.sql
select count(syn.id) cntSynonyms, count(tag.id) cntFoundTargetTagNames from tagSynonyms syn left join tags tag on syn.targetTagname = tag.tagName
Github repository data-stackexchange, path: /erd/analysis/tagSynonyms-joinTargetTagName.sql